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July 1992 
Volume 37, Number 7 

ISSN 009891 42-RECACP 



Conference on 

Emergency Respiratory Care 

Part II 

Emergency Ventilation Techniques and 

Airway Management Options 

Thoracic Trauma 

Emergency Hyperbaric Treatment 

Monitoring during Resuscitation 

Blood Flow during Closed-Chest CPR 

Intrahospital Transport of Mechanically 
Ventilated Patients 

Air Medical Transport 

Conference Summary 





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BC.3. BGEIuclrolyIe>. I.Ml'ACT Blood Gjs Dalj .Mjnagunicnl System jnd |H2 
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© 1992. Instaimentation Laboratory Company 

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has solutions. 

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Broad line of high quality control products for 
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QC Systems"' and Confirmation " Services for 
clinical chemistry and blood gas QC peer 
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Services that help you meet 
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• QC Seminar Program — educates and 
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Circle 102 on reader service card 


A Moiuhlv Science Journal. Esiablished \')>b. Official Jomnal of the American Association lor Respiratory Care. 


Dallas TX 75229 


Pat Brougher RRT 


Philip Killredge RRT 


Donna Stephens BBA 


Neil R Maclniyre MD, Chairman 
Thomas A Barnes EdD RRT 
Richard D Branson RRT 
Robert L Chatbum RRT 
Charles G Durbin Jr MD 
Thomas D Easi PhD 
Dean Hess MEd RRT 
Robert M Kacmarek PhD RRT 
David J Pierson MD 
James K Stoller MD 


Frank E Biondo BS RRT 
Howard J Birenbauni MD 
John G Burford MD 
Bob Demcrs BS RRT 
Douglas B Eden BS RRT 
Donald R Elton MD 
Roben R Fluck Jr MS RRT 
Ronald B George MD 
James M Hurst MD 
Charles G lr\in PhD 
MS Jastremski MD 
Hueh S Mathewson MD 
Michael McPeck BS RRT 
Richard R Richard BS RRT 
John Shigeoka MD 
R Bnan Smith MD 
Jack Wanger RCPT RRT 
Jeffrey J Ward MEd RRT 


Stephen M Ayres MD 
Reuben M Ctierniack MD 
Joseph M Civetta MD 
John B Downs MD 
Donald F Egan MD 
Garelh B Gish MS RRT 
George Gregorv' MD 
H Fredenck Helmholz Jr MD 
John E Hodgkin MD 
William F Miller MD 
Elian J Nelson RN RRT 
Thomas L Petty MD 
Alan K Pierce MD 
Henning Pontoppidan MD 
John W Se\ennghaus MD 
Barry A Shapiro MD 


Linda Barcus 
Steve Bowden 
Donna Knauf 
Jeannie Marchanl 


July 1992 
Voluiiie 37, Number 7 


Part II 

The Proceedings of a Conference 

held October 3-5, 1991, 

in Cancun, Mexico 

Charles G Durbin Jr MD and Thomas A Barnes EdD RRT 
Chairmen and Guest Editors 


673 Emergency Ventilation Techniques and Related Equipment 
by Thomas A Barnes— Boston, Massachusetts 

Airway Management Options 

b\ H David Reines— Richmond, Virginia 

Thoracic Trauma 

by James M Hurst— Tampa. Florida 

Hyperbaric Treatment of Respiratory Emergencies 

by Lindell K Weaver—Salt Lake City, Utah 

Monitoring during Resuscitation 

by Dean Hess and David Eitel—York. Pennsylvania 

The Role of Transesophageal Echocardiography in Determining 

the Mechanism of Forward Blood Flow during Closed-Chest CPR 

by Thomas Porter. Joseph P Ornato. and JV Nixon— Richmond. 


Intrahospital Transport of Critically 111. Mechanically Ventilated 


b\ Richard D Branson— Cincinnati. Ohio 

Air Medical Transport in 1991 

by MarDiene Jeffs— Salt Uike City. Utah 

Conference Summary 

by Charles G Durbin Jr— Charlottesville, Virginia 









Respiratorv Care (ISSN 00989142) is a monthly publication of Daedalus Enterpnses Inc for the Amencan Association for Respiratory Care Copyright «> 1992 by Daedalus En- 

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July 1992 
Volume 37, Number 7 

8 1 3 CRCE through the Journal 


646 Summaries of Pertinent Articles from Other Journals 


824 Meeting Dates. Locations, Themes 


825 Examination Dates. Notices. Prizes 


826 Information for Authors and Typists 


832 Authors in This Issue 
832 Advertisers in This Issue 
654 Advertiser Help Lines 




Summaries of Pertinent Articles in Other Journals 

Editorials, Reports, and Reviews To Note 

Air Travel and Oxvgcn Therapv in Cardiopulmonary Patients (Review). H Gong 
Jr. Chest 1992; 101: 1104. 

Infant Pulmonary Function Testing Workshop .\naheim, California, May 11, 
1991 (ConlL-reiiLL' Report) — J .Allen, N Bashir, R Brown, R Castile. Pediatr Pul- 
monol 1992:12:263. 

The Conundrum of Wheezing and Airway Hyperreactivity in Infancy (Editorial). 
LM Taussig. Pediatr Pulmonol 1992:1.^:1. (Pertains to Tepper et al artiele abstracted 

The Nutritional Importance of Inositol and the Phosphoinositides (Editorial) — 
Holub BJ. N Engl J Med 1992:326:1285. (Pertains to Hallman et al article abstracted 
on Page 656.) 

Tuberculosis Control: Back to the Future? (Editorial). F Gordin. JAMA 
1992:326; 1427. (Pertains to Dooley et al article abstracted on Page 662.) 

Exercise Testing and Reconditioning in Heart and Lung Disease (Supplement). 
CF Donner. L Tavazzi. Chest 1992;I01(Suppl to May). 

The Primary Prevention of Myocardial Infarction (Review) — JE Manson. H 
Tosteson. PM Ridker, S Sattertield. P Hebert. GT O'Connor, et al. N Enal J Med 

Learning Medicine: Too Many Books, Too Few Journals (Editorial). JP Kassirer. 
N Engl J Med 1992;326:1427. 

.Airway Responsiveness in Infants 
Following Bronchiolitis — RS Tep- 
per. D Rosenberg. H Eigen. Pediatr 
Pulmonol 1992:13:6. 

SUMMARY: Airway respon- 
siveness to inhaled methacholine was 
assessed in 18 infants. 4 and 10 
months old, following bronchiolitis. 
Pulmonary function was measured 
from partial expiratory flow-volumes 
curves generated b\ the rapid com- 
pression technique. Sleeping infants 
inhaled increasing concentrations of 
methacholine until maximal expir- 
atory tlows at functional residual 

capacity (VmaxFRC) decreased by 
30% or 2.5 mg/mL was inhaled. Air- 
way responsixeness was quantitated 
by ( 1 ) the threshold concentration 
(log TC) required to decrease 
VmaxFRC by 2 standard deviations 
from baseline; (2) the concentration 
required to decrease VmaxFRC by 
30% (log PC30); and (3) the slope of 
the dose-response curve between TC 
and PC30 (log SPC30). At both the 
first and second evaluation, the bron- 
chiolitic infant had lower baseline 
V,„axFRC (9f pred) than 24 control 
infants. In addition, the bronchiolitic 
infants had heightened airwax 
responsiveness compared to controls. 

demonstrating lower xalues for log 
TC and log PC30 and steeper slopes 
to their dose-response curves (log 
SPC30). After accounting for the 
relationship betx\een airway respon- 
siveness and age. the occurrence of 
bronchiolitis was found to be a sig- 
nificant independent factor 10 
months but not 4 months following 
bronchiolitis. The bronchiolitic 
infants did not demonstrate the 
decline in airway responsiveness 
with increasing age that occurs in 
nonnal infants. We conclude that 
infants exhibit heightened airway 
responsiveness following bron- 




intratracheal suspension 

8 ml Single Dose Vtal 




Sterile Suspension 
Pof Intratracheal 
Administration Only- 
Not For Injection 


1 STOW wr tore 

From Ross Laboratories — 
Helping Premature Babies Survive 

Please see adjacent column for Brief Summary of prescribing information. 


® 1992 Ross Latx>ratories 

OvtSNXi Dt Abbott Laboratories 


Circle 125 on reader service card 

BRIEF SUMMARY Please see package 

insert lor lull prescribing inlormation 

SURVANTA^ (1040) 


intratracheal suspension 

Sletile Suspension For Intratracheal Use Only 


SURVANTA IS indicated for prevention and 
treatment (rescue ) ot Respiratory Distress 
Syndrome (RDSI (hyaline membrane disease) 
in premature infants SURVANTA significantly 
reduces the incidence ol RDS mortality due to 
RDS and air leak complications 

In premature inlants less than 1250 g birth 
weight or with evidence ol surfactant defi- 
ciency, give SURVANTA as soon as possible, 
preferably within 15 minutes of birth 

To treat infants with ROS confirmed by x-ray 
and requiring mechanical ventilation, give 
SURVANTA as soon as possible, preferably by 
8 hours of age 
None known 
SURVANTA IS intended tor intratracheal use only 

fore. Its use should be restricted to a highly 
supervised clinical setting with immediate 
availability of clinicians experienced with intu- 
bation, ventilator management and general 
care of premature infants Infants receiving 
SURVANTA should be frequently monitored 
with arterial or transcutaneous measurement 
ol systemic oxygen and carbon dioxide 

HAVE BEEN REPORTED If these occur stop 
the dosing procedure and initiate appropriate 
measures to alleviate the condition After sta- 
bilization, resume the dosing procedure 

Rales and moist breath sounds can occur 
transiently after administration Endotracheal 
suctioning or other remedial action is not 
necessary unless clear-cut signs of airway 
obstruction are present 

Increased probability of post-treatment 
nosocomial sepsis m SURVANTA-treated 
infants was observed in the controlled clinical 
trials (Table 3) The increased risk for sepsis 
among SURVANTA-treated infants was not 
associated with increased mortality among 
these infants The causative organisms were 
similar m treated and control infants There 
was no Significant difference between groups 
m the rate of post-treatment infections other 
than sepsis 

Use of SURVANTA in infants less than 600 g 
birth weight or greater than 1750 g birth 
weight has not been evaluated m controlled 
trials There is no controlled experience with 
use of SURVANTA in conjunction with experi- 
mental therapies for RDS (eg, high-frequency 
ventilation or extracorporeal membrane 

No information is available on the effects ol 
doses other than 100 mg phospholipids kg, 
more than four doses, dosing more frequently 
than every 6 hours, or administration after 
48 hours of age 

Carcinogenesis. Mutagenesis. 
Impairment of Fedllity 
Reproduciion siudies mammals have not been 
completed Mutagenicity studies were nega- 
tive Carcinogenicity studies have not been 
performed with SURVANTA 

The most commonly reported adverse experi- 
ences were associated with the dosing pro- 
cedure In the multiple-dose controlled 
clinical trials, transient bradycardia occurred 
with n 9% of doses Oxygen desaturation 
occurred with 9 8% of doses 

Other reactions during the dosing pro- 
cedure occurred with fewer than l°o ol doses 
and included endotracheal tube reflux, pallor, 
vasoconstriction, hypotension, endotracheal 
tube blockage, hypertension, hypocarbia. 
hypercarbia, and apnea No deaths occurred 
during the dosing procedure, and all reac- 
tions resolved with symptomatic treatment 

The occurrence of concurrent illnesses 
common m premature infants was evaluated 
in the controlled trials The rates in all con- 
trolled studies are m Table 3 

Ul Contralled SMIes 







Pileni duciin inetKisus 


t? 1 


Inlfacnni* nwrtoirlyge 




Severe tnltKrinul 



Puimoiufy vt leaw 



<0 001 

Pulmofary iniertlilal 



MecrWinng emerocobis 






42 5 


Posi rfejtmeni sepus 
Poslltejlment intection 


16 t 

10 2 



Pulmorury tietTKHrluge 




'P'vatue comparing groups tn controlled studies 

When all controlled studies were pooled, 
there was no difference m intracranial hemor- 
rhage Hovrever, m one of the smgle-dose res- 
cue studies and one of the multiple-dose 
prevention studies, the rate ol intracranial 
hemorrhage was significantly higher m 
SURVANTA patients than control patients 
[63 3% k- 30 8%. P - 001 and 48 8% v 
W 2\. P-0 047, respectively) The rate m 
a Treatment IND involving approximately 4400 
infants was lower than in the controlled trials 

In the controlled clinical trials, there was 
no effect of SURVANTA on results ol common 
laboratory tests white blood cell count 
and serum sodium, potassium bilirubin, 

More than 3700 pretrealment and post- 
treatment serum samples were tested by 
Western Blot immunoassay for antibodies to 
surfactant-associated proteins SP-B and 
SP-C No IgG or IgM antibodies were 

Several other complications are known to 
occur in premature infants The following 
conditions were reported m the controlled 
clinical studies The rates of the complica- 
tions were not different in treated and control 
infants, and none of the complications were 
attributed to SURVANTA 
Respiratory lung consolidation, blood from 
the endotracheal tube, deterioration after 
weaning, respiratory decompensation, sub- 
glottic stenosis, paralyzed diaphragm, respi- 
ratory failure 

Cardiovascular hypotension, hypertension, 
tachycardia ventricular tachycardia, aortic 
thrombosis, cardiac failure, cardio- 
respiratory arrest, increased apical pulse, 
persistent fetal circulation, air embolism, total 
anomalous pulmonary venous return 
Gastromlestinal abdominal distention, hem- 
orrhage, intestinal perforations, volvulus, 
bowel infarct, feeding intolerance, hepatic 
failure, stress ulcer 
Rer}al renal failure, hematuria 
Hematologic coagulopathy, thrombo- 
cytopenia, disseminated intravascular 

Central Nervous System seizures 
Endocrine Metabolic adrenal hemorrhage, 
inappropriate ADH secretion, hyper- 

Musculoskeletal inguinal hernia 
Systemic fever, deterioration 

Follow-up Evaluations 

To date, no long-term complications or 
sequelae of SURVANTA therapy have been 


Single-Dose Studies 

Six-month ad|usted-age follow-up evaluations 
ol 232 infants (115 treated) demonstrated no 
clinically important differences between 
treatment groups m pulmonary and neu- 
rologic sequelae, incidence or severity of reti- 
nopathy of prematurity, rehospitalizations. 
growth or allergic manifestations 

Multipte-Dose Studies 

Six-month adjusted age follow-up evaluations 
have not been completed Preliminarily, in 
605 (333 treated) of 916 surviving inlants, 
there are trends lor decreased cerebral palsy 
and need (or supplemental oxygen m 
SURVANTA infants Wheezing at the time of 
examination tended to be more frequent 
among SURVANTA infants, although there 
was no difference m bronchodilator therapy 

Twelve-month lollow-up data from the mul- 
tiple-dose studies have been completed in 
328 (171 treated) ot 909 surviving inlants To 
date no significant differences between treat- 
ments have been found, although there is a 
trend toward less wheezing in SURVANTA 
infants in contrast to the six month results 


Overdosaae with SURVANTA has not been 
reported Based on animal data, overdosage 
might result m acute airway obstruction 
Treatment should be symptomatic and 

Rales and moist breath sounds can tran- 
siently occur after SURVANTA is oiven. and 
do not indicate overdosage Endotracheal 
suctioning or other remedial action is not 
required unless clear-cut signs ol airway 
obstruction are present 


SURVANTA (beractant) Intratracheal Suspen- 
sion IS supplied in smgle-use glass vials 
containing 8 mL ol SURVANTA (NDC 
0074-1040-08) Each milliliter contains 25 mg 
of phospholipids (200 mg phospholipids 
8 mL) suspended m 9% sodium chloride 
solution The color is olf-white to light brown 
Store unopened vials at refrigeration tem- 
perature (2-8 C) Protect Irom light Store 
vials in carton until ready lor use Vials are lor 
single use only Upon opening, discard 
unused drug 

June. 1991 

B401 2920 



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New jobs listed 
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Airway Pressure Triggered Ven- 
tilation for Preterm Neonates — A 

GrceiiDUgh. MI- Hird. V Chan. J Per- 
inatMed IWI; 19:471. 

The usefulness of airway pressure 
triggered \entilation (PTV) for the 
preterm nev\born has been assessed 
using a new patient triggered valve- 
less ventilator, the SLE 2000 infant 
ventilator (SLE 2000). This ven- 
tilator performs well at fast rates 
with no inadvertent positive end- 
expiratory pressure (PEEP) even at 
rates of 150 bpm. The ventilator is 
triggered by a change in airway pres- 
sure equal to or exceeding 0.5 cm 
HiO. If the infant fails to achieve the 
change in airway pressure that will 
trigger the ventilator, the infant is 
ventilated at the back-up rate which 
is predetermined in conventional 
mode prior to commencing PTV. 
Infants were ventilated for 1 hour on 
a conventional neonatal ventilator. 
then for 1 hour on the SLE 2000 m 
conventional mode without changing 
the ventilator settings, and tmally for 
I hour on the SLE 2000 in patient 
triggered mode. Arterial blood gases 
were checked at the end of each 
hour. During PTV, the peak pressure, 
inspiratory time, and inspired oxygen 
concentration were the same as those 
used during conventional mode. 
Simultaneous recordings were made 
of flow, volume, ventilator and 
oesophageal pressure change; from 
this recording, the trigger delay dur- 
ing PTV was calculated. The trigger 
delay, being the time lag from the 
start of spontaneous inspiration, indi- 
cated by the negative deflection in 
the oesophageal pressure trace and 
the onset of the ventilator breath. 
Thirteen infants were included in the 
study, median gestational age 32 
weeks (range 25-35) and birthweight 
1,640 g (range 838-3,038). All were 
being ventilated for respiratory dis- 
tress syndrome (RDS) and were 4 
days of age. The median trigger 
delav was shown to be 80 msecs 

(range 40-100) and no phase shift 
was demonstrated between inspira- 
tion and inflation. The median PaO: 
following I hour on the conventional 
ventilator was 55 torr (range 47-92) 
and Paco: was 36 torr (range 26-57). 
The arterial blood gases tended to 
improve, but not significantly; fol- 
lowing 1 hour on the SLE ventilator 
in conventional mode, the median 
PjO; increased to 64 torr (range 42- 
94) and the Paco: decreased to 32 torr 
(range 25-46). Following 1 hour of 
PTV. both PaO: and PaCO; were sig- 
nificantly improved, being a median 
of 68 torr (range 45-104). (p < 0.01 ) 
and 29 torr (range 18-40) (p < 0.01). 
respectively. We conclude airway 
pressure triggered PTV using the 
new valveless SLE 2000 infant ven- 
tilator is a useful form of neonatal 

Sympathetic Blockade Enhances 
Blood Flow before Hyperbaric 
Oxygen Therapy — ES Wegr- 
zynowicz. KS Pearson, RE Wachtel. 
J Hyperbaric Med 1991;6(4);249. 

Two patients with ischemic distal 
upper extremity lesions were evalu- 
ated for hyperbaric oxygen (HBO) 
therapy. These patients were initially 
deemed unsuitable for HBO therapy 
because transcutaneous oxygen 
measurements failed to confirm ade- 
quate blood flow to the affected 
areas. Local anesthetic sympath- 
ectomy, however, resulted in an 
increase in blood flow to the 
ischemic areas sufficient to make 
HBO therapy effective. 

The Health and Developmental 
Status of Very Low-Birthweight 
Children at School Age — MC 

McCormick, J Brooks-Gunn. K 
Workman-Daniels. J Turner. GJ 
Peckham. JAMA I992;267:2204. 

OBJECTIVE: To assess the effect of 
improved survival of increasingly 
premature infants by examining the 
outcomes at school age of a large 

group of children bi)m at different 
birthweights. DESIGN: Inception 
Participants were selected from two 
previously studied nuiltisite cohorts: 
very low-birthweight (< 1.5(J0 g) 
children referred to participating 
intensive care units and heavier 
birthweight children drawn from a 
stratified random sample of births in 
geographically defined regions. Fol- 
low-up at 8 to 10 years of age was by 
a combination of telephone interview 
and home/clinic visits for 65.1% 
(1,868) of those eligible. MAIN 
ence or absence of 1 7 specific condi- 
tions, limitations in activities of daily 
living due to health, mental health 
(affective health, behavior problems) 
and. for a subset, IQ scores. 
RESULTS: Decreasing birthweight 
was associated with an increased 
morbidity for all measures except 
affective health; those with birth- 
weights of 1.500 g or less were more 
likely to experience multiple health 
problems. Maternal educational 
attainment did not influence the asso- 
ciation of birthweight with morbidity 
except for IQ among children whose 
birthweight was above 1.000 g. for 
which socioeconomic disadvantge 
worsened the status of all children 
irrespective of birthweight. CON- 
CLUSIONS: Children bom at lower 
birthweights experience increased 
mobidity at early school age. These 
results reinforce the importance of 
postdischarge. early intervention pro- 
grams to reduce the risk of these 
later health problems. 

Incentive Spirometry versus Rou- 
tine Chest Physiotherapy for Pre- 
vention of Pulmonary Complica- 
tions after Abdominal Surgery — 

JC Hall. R Tarala. J Harris. J Tapper, 
K Christiansen. Lancet 1991 ;337: 

We entered 876 patients into a clin- 
ical trial aimed at preventing pul- 



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Circle 132 on reader service card 


monary complications after abdomi- 
nal surgery. Patients either recei\ed 
conventional chest physiotherapy or 
were encouraged to perform maxi- 
mal inspiratory manoeuvres for 5 
min during each hour while awake, 
using an incenti\e spirometer. The 
incidence of pulmonary complica- 
tions did not differ significantly 
between the groups: incenti\e spi- 
rometry 68 of 431 ( 13.8'i. 95'^c con- 
fidence interval [CI] 14.0-17.6%), 
and chest physiotherapy 68 of 445 
(13.3'r, CI 13.6-17.0%). Nor was 
there a difference between the 
groups in the incidence of positive 
clinical signs, pyrexia, abnormal 
chest radiographs, pathogens in spu- 
tum, respiratory failure (Po: < 60 
torr), or length of stay in hospital. 
We conclude that prophylactic incen- 
tive spirometry and chest physio- 
therapy are of equivalent clinical 
efficacy in the general management 
of patients undergoing abdominal 

Oxygen Saturation by Pulse Oxim- 
etry in Healthy Infants at an Alti- 
tude of 1,610 m (5,280 ft): What Is 
Normal?— EH Thilo, B Park- 
Moore, ER Berman, BS Carson. 
AJDC 1991:145:1137. 

Pulse oximetry is a valuable, non- 
invasive technique for assessing oxy- 
gen saturation that has gained wide 
clinical acceptance despite little 
available information concerning 
normal values in the newborn, espe- 
cially at an altitude different than sea 
level. We performed serial pulse ox- 
imetry studies on 150 term, appropri- 
ate-weight-for-gestational-age, clin- 
ically healthy infants at an altitude of 
1,610 m (5,280 ft) at 24 to 48 hours, 
1 month, and 3 months of age to 
define a reference range for oxygen 
saturation as a guideline in clinical 
care. We found that mean oxygen 
saturation at 24 to 48 hours of age is 
92% to 93% and varies little with 
infant activity. With increasing post- 

natal age, there is a tendency for 
increased oxygen saturation during 
the awake states to 93% to 94%, 
while oxygen saturation during sleep 
stays the same or even decreases 
slightly. The lower end of the refer- 
ence range (2 SDs below the mean) 
is as low as 85^7^ during feeding at 24 
to 48 hours of age, and as low as 
86% during quiet sleep at 1 and 3 
months of age, with 88% to 89% the 
lower limit in other activities at all 

Gastroesophageal Reflux and Ap- 
nea in Prematurely Born Infants 
during Wakefulness and Sleep — M 

de Ajuriaguerra, M-F Radvanyi- 
Bouvet, C Houn. G Moriette. AJDC 

The hypothesis that acid gastro- 
esophageal reflux may be respon- 
sible for the persistence of apnea was 
tested on 20 prematurely bom 
infants, at a median conceptional age 
of 38.7 weeks. Gastroesophageal 
reflux was identified using distal 
esophageal pH monitoring. Apneas 
of durations greater than 10 seconds 
were identified and classified as 
either central or obstructive and 
mixed, using recordings of respira- 
tion. Wakefulness, active sleep, and 
quiet sleep were identified using 
electroencephalography and by 
assessing eye movements. Of 134 
episodes of acid gastroesophageal 
reflux in the 20 subjects, more 
occurred during wakefulness and 
during active sleep than during quiet 
sleep. A total of 139 apneas, pre- 
dominantly of the obstructive and 

mixed type, occurred. No relation- 
ship could, however, be denH)n- 
strated, in this rather small number 
of patients, between the occurrence 
of gastroesophageal reflux and that 
of apneas. 

Lung Function Measurements in 
Awake Compared to Sleeping 
Newborn Infants — KC Lodrup. P 
Mowinckel. KH Carlsen. Pediatr 
Pulmonol 1992;12:99. 

Tidal breathing flow-\olume loops 
were recorded in 19 healthy newborn 
infants when awake and asleep. This 
preceded and followed measure- 
ments of passive lung mechanics (by 
single breath occlusion). Our aim 
was to evaluate possible differences 
in lung function due to state of arou- 
sal or any influence of the occlusion 
technique. Expiratory \olumes and 
flowrates were larger in awake than 
in sleeping infants before, but not 
after occlusion measurements. In 
sleeping, but not in awake infants, 
expiratory volumes and flowrates 
were higher after occlusion than 
before. Respiratory system com- 
pliance was significantly larger in 
sleeping than awake infants, while 
differences in respiratory system 
resistance and airway plateau pres- 
sure did not reach a significant level. 
Our results show that lung function 
can be measured in awake as well as 
sleeping infants, but differs signif- 
icantly according to their arousal 
state, and whether tidal expiratory 
flow measurements are perforined 
before or after airway occlusion 
measurements. Separate reference 


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values for awake and sleeping 
infants may, therefore, be required. 
Marked intrasubject variability uas 
found in the occlusion measure- 
ments, and criteria for acceptable 
measurements need to be defmed. 

Adverse Effects of Prolonged 
Hyperventilation in Patients with 
Severe Head Injury: .\ Ran- 
domized Clinical Trial — JP Mui- 
zelaar. A Marmarou. JK Ward, HA 
Kontos. SC Choi. DP Becker, et al. J 
Neurosurg 1991:75:731. 

There is still controversy over 
whether or not patients should be 
hyperventilated after traumatic brain 
injury, and a randomized trial has 
never been conducted. The theoret- 
ical advantages of hyperventilation 
are cerebral vasoconstriction for 
intracranial pressure (ICP) control 
and reversal of brain and cere- 
brospinal fluid (CSF) acidosis. Pos- 
sible disadvantages include cerebral 
vasoconstriction to such an extent 
that cerebral ischemia ensues, and 
only a short-lived effect on CSF pH 
with a loss of HCO. buffer from 
, CSF. The latter disad\ antage might 
be overcome by the addition of the 
buffer tromethamine (TH.'XM), 
which has shown some promise in 
experimental and clinical use. 
Accordingly, a trial was performed 
with patients randomly assigned to 
receive normal ventilation (PaCO; 
35 ± 2 torr [mean, SD]: control 
group), hyper\entilation (PaCO: 
25 ± 2 torr: HV group), or hyper- 
ventilation plus THAM (PaCO: 25 ± 2 
torr: HV + THAM group). Strat- 
ification into subgroups of patients 
with motor scores of 1-3 and 4-5 
took place. Outcome was assessed 
according to the Glasgow Outcome 
Scale at 3. 6. and 1 2 mo. There were 
41 patients in the control group, 36 
in the HV group, and 36 in the 
HV -I- THAM group. The mean 
Glasgow Coma Scale score for each 
group was 5.7 ± 1.7, 5.6 ± 1.7, and 

5.9 ± 1.7, respectively; this score 
and other indicators of severity of 
injury were not significantly differ- 
ent. A lOOCf folU)w-up review was 
obtained. At 3 and 6 mo after injury, 
the number of patients with a favor- 
able outcome (good or moderately 
disabled) was significantly (p < 
0.05) lower in the hyperventilated 
patients than in the control and 
HV -I- THAM groups. This occurred 
only in patients with a motor score of 
4-5. At 12 mo post-trauma, this dif- 
ference was not significant (p - 
0.13). Biochemical data indicated 
that hyper\entilation could not sus- 
tain alkalinization in the CSF, 
although THAM could. Accordingly, 
cerebral blood flow (CBF) was lower 
in the HV -i- THAM. It is concluded 
that prophylactic hyperventilation is 
deleterious in head-injured patients 
\\ ith motor scores of 4-5. When sus- 
tained hyperventilation becomes nec- 
essary for ICP control, its deleterious 
effect may be overcome by the addi- 
tion of THAM. 

Variability of Dynamic Compli- 
ance Measurements in Spontane- 
ously Breathing and Ventilated 
Newborn Infants — FA Ratjen. HG 
Wiesemann. Pediatr Pulmonol 1992; 

We studied reproducibility and var- 
iability of dynamic pulmonary com- 
pliance (Cdsn) by making measure- 
ments with the esophageal balloon at 
multiple locations within the esoph- 
agus, in both spontaneously breath- 
ing and mechanically \entilated new- 
bom infants. Reliable measurements 
could be obtained over a range sim- 
ilar to that reported for measure- 
ments with a liquid-filled catheter. In 
spontaneously breathing infants Cd\n 
was found to be highly \ariable. This 
variability was unrelated to catheter 
position but was associated with con- 
comitant changes in pulmonary resis- 
tance. Probably because of the high 
variability, the correlation of Cdyn 

with a measurement of respiratory 
system compliance (Crs) was rather 
poor (r = 0.63). Cd>n measured in 
mechanically \entilated infants was 
significantly less \ariable and com- 
pared favorably to Crs (r = 0.86). but 
its accuracy could not be adequately 
assessed since the comparison of 
esophageal and airway occlusion 
pressure was not feasible in all 
infants. In addition, significant dif- 
ferences in Cdyn were found between 
spontaneously and ventilated breaths 
during mechanical ventilation. Fur- 
ther studies in both ventilated and 
spontaneously breathing infants are 
needed to assess the variability of 
Cdyn over extended time periods. 

The Efficacy of Nebulized Meta- 
proterenol in Wheezing Infants 
and Young Children — AJ Alario. 
WJ Lewander, P Dennehy. R Seifer, 
AL Mansell. AJDC 1992:146:412. 

The benefit of /j-adrenergic agonists 
in the treatment of acutely wheezing 
infants and young children has not 
been well documented in the out- 
patient setting. To determine the effi- 
cacy of nebulized metaproterenol 
sulfate, 74 children aged 36 months 
or younger with acute wheezing par- 
ticipated in a double-masked, ran- 
domized, placebo-controlled clinical 
trial. Children recei\'ed nebulized 
metaproterenol. either as an initial 
treatment or after a control treatment 
with normal saline solution. At base- 
line and 20 minutes after each treat- 
ment, an assessment was made that 
included measurements of heart rate. 
respiratory rate, oxygen saturation, 
and clinical variables related to res- 
piratory compromise with the use of 
a standardized respiratory distress 
index (RDl). Children who received 
saline solution as initial therapy had 
no significant differences from base- 
line in any of the assessment meas- 
ures. After metaproterenol therapy, 
children demonstrated an increase in 
heart rate (mean [SD] 147 [14] beats/ 





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Bear Medical Systems 800-BE.AR-MED 

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Ciba-Corning Diagnostics 800-255-3232 

Dc> Laboratories 800-755-5560 

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The Latest On 


ARDS Review: 1990 
By Tony Dal Nogare, MD 

ARDS was originally described in 1967 and has 
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ARDS in 1990 discusses the latest developments 
in risk factors and treatment. Also covers the 5 
diagnostic criterio that must be present to make 
an accurate diagnosis of ARDS, including 
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Our patented flow-sampling technology, 
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min vs 153 |l(i| beats/min). a de- 
crease in respirations (50 |5] vs 45 
|7|/min). improvement (lower scores) 
on the RDI (24 [4] vs 15 [2|). and an 
increase in oxygen saturation (94.1 
[2.7] '7c vs 95.3 [3.01 '7c). Patients 
aged 12 months or younger (n = 37) 
benefited from melaproterenol treat- 
ment (improvement in respiratory 
rate and RDI) but not to the same 
degree as children aged 24 months or 
older (n = 23) (improvement in res- 
piratory rate, RDI, and oxygen sat- 
uration). Compared with assessments 
made before metaproterenol treat- 
ment, patients with respiratory syn- 
cytial virus infection (n = 21) had 
improvement in respirations (52 [7] 
vs 45 [6]/min) and RDI scores (22 
[4] vs 14 |3|). Based on a priori cri- 
teria (reduction in a premedication 
respiratory rate of 20% and an RDI 
score of 50'7r), responders to meta- 
proterenol therapy included 45% of 
the entire sample and. respectively, 
40% of those aged 12 months or 
younger. 52% of those aged 24 
months or older, and 48% of patients 
who tested positive for respiratory 
syncytial virus. Although there 
appears to be an age-dependent 
degree of response, metaproterenol is 
effective in relieving the respiratory 
distress of young acutely wheezing 
children, including those with doc- 
umented respiratory syncytial virus 

How Much 'Better' Is (lood 
Enough?: The Magnitude of 
Treatment Kffect in Clinical 
Trials — TNK RajU, P Langenberg. 
A Sen, O Aldana. AJDC 1992:146: 

OBJECTIVES: Among the various 
factors required to calculate sample 
size for clinical trials, the magnitude 
of treatment effect anticipated is an 
important component. The objective 
of this report is to present some of 
the complexities inNolved in a selec- 

tion of treatment effect size in clin- 
ical trials. As a framework for dis- 
cussion, an analysis of published 
reports related to surfactant therapy 
was carried out. DESIGN: 21 con- 
secutive exogenous surfactant trials 
for neonatal respiratory distress syn- 
drome were analyzed. The "Meth- 
ods" sections were reviewed for 
evaluating various components of 
sainple size calculation, including 
the anticipated treatment effect size. 
RESULTS: 16 (76%) of the 21 
reports provided a description of 
sample size calculations, and 12 of 
these gave some reasons for the 
choice of the anticipated treatment 
effect size. Expressed as percent 
change, the median treatment effect 
from intervention anticipated by the 
investigators was 50% (range 15% to 
90%), with a positively skewed dis- 
tribution. The actual median percent 
reduction in adverse events from 
treatment (as compared with base- 
line) was 36% (range 75% reduction 
to 5% excess). When the treatment 
effect was expressed as difference in 
adverse event rate, in the 14 (of 16) 
trials that could be analyzed, the 
median observed reduction in 
adverse events (death, broncho- 
pulmonary dysplasia, or occurrence 
of respiratory distress syndrome) was 
14.5% (range 52% reduction to 2% 
excess). All trials except one con- 
cluded. ho\\e\er, that the inter- 
vention v\as effecti\e, mostly based 
on additional subgroup calculations. 
CONCLUSIONS: Researchers often 
select sample sizes capable of detect- 
ing only large treatment effects, thus 
risking Type II error, although some- 
times a much smaller effect could be 
clinically important. While prag- 
matic considerations must be con- 
sidered during the design of random- 
ized clinical trials, researchers ought 
to present a rationale for anticipating 
a gi\en magniliiile of treatment 
effect in their sample size calcula- 
tions. It mas be possible to consider 
inno\ alive lri;il designs that help 

determine the most appropriate treat- 
ment choice with the least possible 
sample size. 

Inositol Supplementation in Pre- 
mature Infants with Respiratory 
Distress Syndrome — M Hallman, K 
Bry. K Hoppu, .\1 Lappi, M Poh- 
javuori. N Engl J Med 1992; 

BACKGROUND: Inositol intluences 
cellular function and organ matura- 
tion. Feeding premature infants inos- 
itol-rich breast milk increases their 
serum inositttl concentrations. 
Whether inositol supplementation 
benefits infants receiving fluids for 
parenteral nutrition, which are inosi- 
tol-free, is not known. METHODS: 
We carried out a placebo-controlled, 
randomized, double-blind trial to 
determine the effects of admin- 
istering inositol (80 mg per kilogram 
of body weight per da\ ) during the 
first five days of life to 221 infants 
with respiratory distress syndrome 
who were receiving parenteral nutri- 
tion (gestational age 24 to 32 weeks; 
birthweight < 2.000 g). .All the 
infants were treated with mechanical 
ventilation and some with surfactant 
as well. The primary end point was 
survival at 28 days without bron- 
chopulmonary dysplasia. RESULTS: 
The 1 14 patients given inositol had 
significantly lower mean require- 
ments for inspiratory oxygen 
(p < 0.0 1 ) and mean airway pressure 
(p <0.()5) from the 1 2th through the 
144th hour of life than did the 107 
infants given placebo. Eighty-one 
infants given inositol and 51 given 
placebo survived without broncho- 
pulmonary dysplasia (71% vs 55%; 
p= 0.005). In the 65 infants given 
surfactant, however, inositol had no 
effect on the degree of respiratory 
failure. Thirteen infants given inos- 
itol and 21 given placebo had reti- 
nopathy of prematurity (13% vs 
269^: p = 0.022): none of the infants 







Model used fofll 


Significant IVH Reduction in 
Infants > 1250 g 

Despite successes in improving the survival 
of infants with RDS, intraventricular hemor- 
rhage (IVH) remains a serious problem.^^ 
However, in a recently reported placebo- 
controlled rescue trial in infants > 1250 g, 
EXOSURF Neonatal actually reducecf the 
incidence of IVH.- In trials of smaller infants 
(<1250 g), EXOSURF Neonatal has never 
been observed to significantly increase IVH. 

Incidence of IVH (All Grades) 





(n = 622) 

P= 0.036 

Two-dose treatment. Incidence of IVH in infants weighing 

1250 g or more. 

Adapted from Long et a\-""""' 

Significant BPD Reduction in 
Infants >1250g 

In the rescue trial involving over 1200 
infants, administration of EXOSURF Neonatal 
significantly reduced the incidence of 
bronchopulmonary dysplasia (BPD) by nearly 
50% (P = 0.021). 

Incidence of BPD Among RDS Survivors 



(n = 614) 


(n = 623) 

P= 0.021 

Two-dose treatment. Incidence of BPD in 28day survivors 
following RDS in infants weighing 1250 g or more 
Adapted from Long et al-'"""" 

No Increase in Sepsis 

No difference in the incidence of sepsis has 
been seen with EXOSURF Neonatal during 
placebo-controlled trials (n = 1517). The 
rate of sepsis was similar in an open trial of 
11,455 infants.^ 

No Animal Proteins 

EXOSURF is purely synthetic and carries no 
known infectious or immunologic risks. 

Other Safety Considerations 

Various forms of pulmonary air leak were 
reduced in all controlled trials. A single con- 
trolled study in infants 500-699 g reported 
a significant increase in pulmonary hemor- 
rhage.' Significant increases in apnea were 
reported in three controlled trials.' ""^ Apnea 
appears to be a marker for improved survival.^ 



(Colfosceril Palmitate, Cct\^ Alcohol, 

TyloXapol) For Intratracheal Suspension/10-mL vial 



Piease see brief summary of full prescribing information on following page. 

' Increased pulmonary hemorrhage was noted in one trial of infants 500-699 g'; 
increased apnea has been noted in some trials. ' ^ * 


(Colfosceril Palmitate, Cetyl Alcohol, 

TYlOXapoI) For Intratracheal Suspension/10-mL vial 


• Increased pulmonary hemorrhage was noted in one trial of infants 500-699 g^; 
increased apnea has been noted m some trials. ' ^ * 


INDICATIONS AND USAGE: Exosu^ Neonatal is indicated tor ^ Prophylactic 

Irealmeni oi infants with Dirth rteigHls ol less than 1350 grams who are ai nsk of 
developing RDS (see PRECAUTIONS), 2 Prophylactic treatment of infants with 
birth weights greater than 1 350 grams who have evidence of pulmonary immaturi- 
ty, and 3 Rescue treatment of infants wt>o have developed RDS. 
CONTRAINDICATIONS: There are no known contraindications to treatment with 
Exosurl Neonatal 

WARNINGS: Intratracheal Administration Only; Exosurt Neonatal should be 
administered only by mslillaljon mlo the trachea (see DOSAGE AND ADMINIS- 
TRATION! General: The use o! Exosurl Neonatal requires expert dmical care by 
expenenced neonatologists and other clinicians who are accomplished at neona- 
tal intubation and ventilatory management Adequate personnel, facilities, equip- 
ment, and medications are required to optimize pennatal outcome in premature 
infants Vigilant dmical attention should be given to all infants pnor to, dunng, and 
afler administration of Exosurf Neonatal Acute Effects: Exosurl Neonatal can 
rapidly affect oxygenation and lung compliance Lung Compliance: If chest 
expansion improves substantially after dosing, peak ventilator inspiratory pres- 
sures should be reduced immediately, without wal^^^g for confirmation of respira- 
tory improvement by blood gas assessment Failure to reduce inspiratory ventila- 
tor pressures rapidly in such instances can result in lung overdislention and fatal 
pulmonary air leak. Hyperoxia: If the mfant becomes pink and transcutaneous 
oxygen saturation is in excess of gs^o FiQ: should be reduced m small but 
repeated steps luntl saturation is 90 to 95% i without waiting for confirmation of 
elevated anenal pO: by blood gas assessment Failure to reduce FiO: in such 
instances can result m hyperoxia Hypocarbia: If artenal or transcutaneous CO? 
measurements are <30 torr, the ventilator rale should be reduced at once Failure 
to reduce ventilator rates in such instances can result in marked hypocarbia. 
which IS known to reduce brain blood flow Pulmonary Hemorrhage: in the sin- 
gle study conducted m infants weighing <700 grams at birth, the incidence of pul- 
monary hemorrhage (ICo vs 2°o in the placebo group) was significantly increased 
in the Exosurf Neonatal group None of the five studies involving infants with birth 
weights >700 grams showed a significant increase m pulmonary hemorrhage in 
the Exosurf Neonatal group In a cross-study analysis of these five studies, fatal 
pulmonary hemorrhage occurred in three infants, two m the Exosurt Neonatal 
group and one in the placebo group Mortality from all causes among infants who 
developed pulmonary hemorrhage was 43% in the placebo group and 37% m the 
Exosurf Neonatal group Pulmonary hemorrhage in both Exosurf Neonatal and 
placebo infants was more frequent m infants who were younger, smaller, male, or 
who had a patent ductus artenosus Pulmonary hemorrhage typically occurred in 
the first 2 days of lite m both treatment groups Mucous Plugs: Infants whose 
ventilation becomes markedly impaired dunng or shortly after dosing may have 
mucous plugging of the endotracheal tube, particularly if pulmonary secretions 
were prominent pnor to drug administration Suctioning of all infants pnor to dos- 
ing may lessen the chance of mucous plugs obstmcting the endotracheal tube it 
endotracheal tube obstaiction from such plugs is suspected, and suctioning is 
unsuccessful m removing the obstruction, the blocked endotracheal lube should 
be replaced immediately 

PRECAUTIONS: General: In the controlled dimcal studies, infants known prena- 
tally or postnatally to have major congenital anomalies, or who were suspected ot 
having congenital infection, were exduded from entry However, these disorders 
cannot be recognized early in life m all cases, and a tew infants with these condi- 
tions were entered The benefits of Exosurf Neonatal in the affected inlants who 
received drug appeared lo be similar to the benefits observed in infants without 
anomalies or occult infection Prophylactic Treatment— Infants <700 Grams: In 
infants weighing 500 to 700 grams, a single prophylactic dose of Exosurf Neonatal 
significantly improved FiO; and ventilator settings, reduced pneumothorax, and 
reduced death from RDS. but increased pulmonary hemorrhage (see WARN- 
INGS) Overall mortality did not differ significantly between the placebo and 
Exosurf Neonatal groups Data on multiple doses in infants m this weight class are 
not yet available Rescue Treatment— Number ol Doses: A small number of 
inlants with RDS have received more than two doses of Exosurf Neonatal as res- 
cue treatment. Definitive data on the safety and efficacy of these additional doses 
are not available Carcinogenesis, Mutagenesis, Impairment of Fertility: 
Exosurf Neonatal at concentrations up to 10.000 ng/plate was not mutagenic m 
the Ames Salmonella assay Long-term studies have not been perlonned in ani- 
mals to evaluate the carcinogenic potential of Exosurf Neonatal The effects of 
Exosurt Neonatal on lerliltty have not been studied. 


General: Premature birth is associated with a high incidence of morbidity and 

mortality Despite significant reductions in overall mortality associated with 
Exosurf Neonatal, some inlants who received Exosurf Neonatal developed severe 
complications and either survived with permanent handicaps or died. In controlled 
dimca) studies evaluating the safety and efficacy of Exosurf Neonatal, numerous 
safety assessments were made In infants receiving Exosurf Neonatal, pulmonary 
hemorrtiage. apnea and use ot melhylxanlhmes were increased A number ol 
other adverse events were significantly reduced in the Exosurf Neonatal group, 
particularly vanous forms of pulmonary air leak and use of pancuronium Reflux: 
Reflux of Exosurf Neonatal into the endotracheal tube dunng dosmg has been 
observed and may be assooated with rapid drug administration If reflux occurs. 

dnjg administration should be hatted and, it necessary peak inspiratory pressure 
on the venltiatof should be inaeased by -l to 5 cm H.-O until the endotracheal tube 
dears >20% Drop in Transcutaneous Oxygen Saturation: If transcutaneous 

oxygen saturation declines dunng dosing drug administration should t* halted 
and, if necessary, peak inspiratory pressure on the ventilator should be increased 
by 4 to 5 cm H.-O for 1 to 2 minutes In addition increases of FiO. may be required 
for 1 to 2 minutes 

DOSAGE AND ADMINISTRATION: Preparation of Suspension: Exosurf 

Neonatal is best reconstituted immediately before use because it does not contain 
antibactenal presen/alives However, the reconstituted suspension is cbemicalty 
and physically stable when stored at 2" to 30 "C (36 lo 86 F| tor up to 12 hours 
following reconstitution Solutions containing buffers or preservatives should not 
be used for reconstitution Do Not Use Bacteriostatic Water lor Injection. USP, 
Each vial of Exosurf Neonatal should be reconstituted only with 8 mL oi the 
accomp^nvinq diluent (preservative-tree Slenie Water for Injection) Dosage: 
Accurate determination ol weight at binh is the key to accurate dosing. 
Prophylactic Treatment: The first dose of Exosurf Neonatal should be adminis- 
tered! ii d iigie 5 mL'kg dose as soon as possible after birih Second and third 
doses should be administered approximately 12 and 24 hours later to all infants 
who remain on mechanical ventilation at those times Rescue Treatment: 
Exosurf Neonatal should be administered in two 5 mUVg doses The initial dose 
should be administered as soon as possible after the diagnosis ol RDS is con- 
firmed The second dose should be administered approximately 12 hours (oltow- 
ing the first dose, provided tlie mfant remains on mechanical ventilation Use of 
Special Endotracheal Tube Adapter: With each vial of Exosurf Neonatal lor 
Intratracheal Suspension five different sized endotracheal tube adapters each 
with a speaal nghl angle Luer'-locK sideporl are supplied The adapters are dean 
but not slenie Administration; The infant should be suctioned pnor to adminis- 
tration of Exosurf Neonatal Exosurf Neonatal suspension is administered via the 
sideporf on the special endotracheal tube adapter WITHOUT INTERRUPTING 
MECHANICAL VENTILATION. Each Exosurf Neonatal dose is administered m 
two 2 5 mbltg halt-doses Each hatf-dose is instilled slowly over l to 2 minutes 
(30 to 50 mechanical breaths] in small bursts tmed with inspiration After the first 
2,5 mbltg hatf-dose is administered m the midline position, the infant s head and 
torso are turned 45 to ttie right for 30 seconds while mechanical venlilafton is 
continued After the infant is relumed lo the midline position, the second 2.5 
mL/kg half-dose is gn/en in an identical fashion over another 1 to 2 minutes. The 
infants head and torso are then turned 45 to the left tor 30 seconds while 
mechanical ventilation is continued, and the infant is then turned back to the mid- 
line posl^on These maneuvers allow gravity to assist m the distnbution of Exosurf 
Neonatal m the lungs Dunng dosing, heart rale, color, chest expansion, faaai 
expressions, the oximeter and the endotracheal lute palencv and position should 
be monitored Suctioning should not be performed for two hours after 
Eiosurf Neonatal is administered, except when dictated by clinical neces- 

HOW SUPPLIED: Exosurf Neonatal lor Intratracheal Suspension is supplied in a 
carton containing one 10 mL vial of Exosurl Neonatal lor Intratracheal 
Suspension, one 10 mL vial of Slenie Water for Injection, and five endotracheal 
tube adapters (2 5, 3 0, 35, 40. and 4 5 mm ID) (NDC 0081-0207-01) Store 
Exosurf Neonatal lor Intratracheal Suspension at 15 lo 30C (59 lo 86 F) in a 
dry place 

EDUCATIONAL MATERIAL: A videotape on dosing is available from your 
Buroughs Wellcome Co representative This videotape demonstrates techniques 
for sale administration of Exosurt Neonatal and should be viewed by health care 
professionals who will administer the daig 
Licensed under US Patent Nos 4312860 and 4826821 500009 

Reterences: 1. Long W. Thompson I Sundell H, ei al Eflecis of two rescue 
doses of a synthetic surfactant on mortality rate and survival without broncho- 
pulmonary dysplasia in 700- to 1350-gram infants with respiratory distress syn- 
drome J Pediatr 1991.118 595-605 2. Long W, Corbet A Conon R. el at A 
controlled inal of synthetic surfactant in infants weighing 1250 g or more with 
respiratory distress syndrome NEngUMed 1991.325 1696-1703 S.SpeerCP, 
Robertson B. Cursledt T el al Randomized European multicenter inal of surfac- 
tant replacement therapy for severe neonatal respiratory distress syndrome 
single versus multiple doses ol Curosurf Pediatrics 1992,89 13-20 4. Horbar 
JO, Soil RF Schachinger H, et al A European multicenter randomized controlled 
tnal of Single dose surfactant therapy for idiopathic respiratory distress syn- 
drome EurJPediair 1990.149 416-423 5. Cowan F Whitelaw A Wertheim D. 
Silverman M Cerebral blood flow velocity changes after rapid adminisuation of 
surfaclani ArchDisChild 1991,66 1105-1109 6. Russell L. White A. Andrews 
E, et al Observational study of synthetic surfactant m 1 1 ,455 infants Presented 
at the 1992 Meeting of the American Pediatric Society/Society for Pedialnc 
Research. May 4-7. 1992. Baltimore. MO 7. Stevenson D. Walther F Long W, et 
al Controlled Inal ol a single dose ol synthetic surfactant at birth in premature 
infants weighing 500 to 699 grams J Pediatr 1992,120 S3S12 8. Corbet A, 
Bucciarelli R, Goldman S, el al Decreased mortality rate among small premature 
infants treated at birth with a single dose of synthetic surfactant a multicenter 
controlled inal JPediatr 1991,118 277-254 

I /\ Burroughs Wellcome Co. 

Wellcome - ;• h [rorQle Rark NC 27709 

Coor t. lyy./ •- , Co All rights res*fvecl 


given inositol had Stage 4 disease, 
whereas 7 of those given placebo did 
(0% vs 9%; p = 0.012). Among the 
infants given placebo, those who had 
poor outcomes (death, broncho- 
pulmonary dysplasia, or Stage 4 reti- 
nopathy of prematurity) had lower 
serum inositol concentrations during 
Days 2 through 7 than those who had 
good outcomes (p<0.01). CON- 
CLUSIONS: The administration of 
inositol to premature infants with 
respiratory distress syndrome who 
are receiving parenteral nutrition dur- 
ing the first week of life is associated 
with increased survival without bron- 
chopulmonary dysplasia and with a 
decreased incidence of retinopathy of 

Nicotine Chewing Gum Use in tiie 
Outpatient Care Setting — RE John- 
son, VK Stevens, JF HoUis, GT 
Woodson. J Fam Pract 1992;34:61. 

BACKGROUND; The purpose of 
this study was to assess nicotine gum 
use when prescribed in a non- 
research, routine outpatient setting. 
Special attention was given to com- 
paring actual use patterns with estab- 
lished guidelines for use based on 
clinical research. METHODS: A ran- 
domly selected group of 612 patients 
who had received a prescription for 
nicotine gum during an 1 8-mo period 
were surveyed regarding their smok- 
ing history and use of the gum. 
RESULTS: Most of the gum pre- 
scriptions (75%) were requested by 
patients rather than recommended by 
medical care providers. Less than 
one half of the users were heavy 
smokers. The reported amount of 
gum used was small, with more than 
one half reporting consumption of I 
box or less, and about one third 
reporting use of the gum for only 1 
week or less. Larger amounts of gum 
use, however, were associated with 
abstinence from tobacco. Only 1 in 
20 users attended a structured behav- 
ioral treatment program while using 

the gum. Over one half of the 
patients reported using nicotine gum 
to help them cut down on, rather than 
quit, smoking. CONCLUSIONS: 
Only a small percentage of the 
patients used the nicotine gum 
according to the established guide- 
lines, and most of the patients used 
the gum in ways that have been 
shown to be ineffective for smoking 
cessation. Providers should educate 
their patients in the techniques that 
ma.ximize the use and effectiveness 
of nicotine gum in smoking cessa- 

The Clinical Course of Pulmonary 
Embolism — JL Carson, MA Kelley, 
A Duff, JG Weg, WJ Fulkerson, HI 
Palevsky, et al. N Engl J Med 

BACKGROUND: Pulmonary embo- 
lism is a potentially fatal disorder. 
Information about the outcome of 
clinically recognized pulmonary 
embolism is sparse, particularly 
given that new treatments for more 
seriously ill patients are now avail- 
able. METHODS: We prospectively 
followed 399 patients with pul- 
monary embolism diagnosed by lung 
scanning and pulmonary angio- 
graphy, who were enrolled in a mul- 
ticenter diagnostic trial. We re- 
viewed all hospitalizations, all new 
investigations of pulmonary embo- 
lism, and all deaths among the 
patients within 1 year of diagnosis. 
RESULTS: Of the 399 patients, 375 
(94%) received treatment for pul- 
monary embolism, usually conven- 
tional anticoagulation. Only 10 
patients (2.5%) died of pulmonary 
embolism; 9 of them had clinically 
suspected recurrent pulmonary em- 
bolism. Clinically apparent pul- 
monary embolism recurred in 33 
patients (8.3%), of whom 45% died 
during follow-up. Ninety-five pa- 
tients with pulmonary embolism 
(23.8%) died within 1 year. The con- 
ditions associated with these deaths 

were cancer (relative risk 3.8; 95% 
confidence interval, CI, 2.3 to 6.4), 
left-sided congestive heart failure 
(relative risk 2.7; 95% CI 1.5 to 4.6), 
and chronic lung disease (relative 
risk 2.2; 95% CI 1.2 to 4.0). The 
most frequent causes of death in 
patients with pulmonary embolism 
were cancer (in 34.7%), infection 
(22.1%), and cardiac disease 
(16.8%). CONCLUSIONS: When 
properly diagnosed and treated, clin- 
ically apparent pulmonary embolism 
was an uncommon cause of death, 
and it recurred in only a small minor- 
ity of patients. Most deaths were due 
to underlying diseases. Patients with 
pulmonary embolism who had can- 
cer, congestive heart failure, or 
chronic lung disease had a higher 
risk of dying within 1 year than did 
other patients with pulmonary embo- 

Acute Respiratory Compromise 
Resulting from Tracheal Mucous 
Impaction Secondary to a Trans- 
tracheal Oxygen Catheter — BJ 

Roth, TW Irvine, DA Liening, NO 
Duncan, WH Cragun. Chest 1992; 

Transtracheal oxygen catheters are 
being increasingly used because of 
savings in oxygen usage and patient 
preference. The complications of the 
catheter are believed to be minor and 
easily managed. Inspissated mucous 
collections that form at the tip of the 
SCOOP 1 (Transtracheal Systems, 
Denver CO) catheter have been 
reported but are usually easily expec- 
torated by the patient. This report 
describes a patient who had develop- 
ment of acute respiratory com- 
promise from crusted mucoid impac- 
tion of the trachea secondary to 
transtracheal catheter use. General 
anesthesia and rigid bronchoscopy 
were required for removal of the 
obstructing iinpaction. Unexplained 
worsening of respiratory symptoms 
in patients with transtracheal oxygen 




















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IMPACT'" Blood Gas Data Manage- 
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quality assurance system. Its low-cost 
networking capability allows you to 
collect data from multiple IL blood gas 
and CO-Oximeter~ analyzers. Store 
the results in one location. Direa 
information wherever it's needed. This 
simplifies QC and maintenance moni- 
toring and increases the efficiency of 
your lab. 


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designed to make CLLA compliance 
effortless and efficient. The system 
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ratory accreditation and certification. 


Tlie system is exceptionally easy to 
use. Patient data entry involves only 
one screen. You simply enter a pass- 
word and the patient's last name or 
ID number Calibration and routine 
maintenance data are captured, and 
reports are generated as required — 
all automatically. Incidentally, if you'd 
like to see how your .statistics com- 
pare with other labs, you can mail 
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AccuTrak* Statistics Services Center. 

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catheters should be addressed 
prompt stripping of the catheter. 


Volume-Cycled Decelerating Flow: 
An Alternative Form of Mechan- 
ical Nentilation — SA Ra\enscraft. 
WC Burke. J J Marini. Chest 1992: 

The linerly decelerating flow wave- 
form for volume-cycled mechanical 
ventilation is an option on man\ 
modem ventilators. We have devel- 
oped mathematical models for two 
available forms of volume-cycled 
decelerating-flow ventilation (VCDF). 
These equations use clinician-chosen 
ventilator settings as inputs (fre- 
quency, tidal volume, peak inspir- 
atory flow or inspiratory time frac- 
tion, and end-inspiratory pause), and 
patient-determined inputs that 
describe the patient's ventilatory 
impedance (inspiratory [Ri] and 
expiratory [Re] resistance and res- 
piratory system compliance [C]). 
The equations predict key outcome 
variables: mean airway pressure; and 
peak. mean, and end-expiratory alve- 
olar pressures. The mathematical 
expressions were validated in a 
mechanical lung analog. Values 
observed in the test lung were com- 
pared to values predicted by the 
mathematical models for a wide 
range of ventilator settings and 
impedance combinations (Ri and Re 
5 to 40 cm H:0 • s/L; C 0.02 to 0.10 
L/cm H:0). The correspondence 
between observed and predicted val- 
ues was generally excellent across 
the broad range of inputs tested 
(r>0.98). Outcome variables were 
quite sensitive to clinician-chosen 
inputs over certain critical ranges. 
Carefully applied. VCDF offers sev- 
eral theoretic advantages for the clin- 
ical setting: however, appropriate 
caution must be exercised to avoid 
the application of tissue-injuring 


Bound Volumes 

The 1991 bound volume of RESPIRATORY CARE is available. The 12 issues of Volume 
36 are bound in a blue buckram cover and can be imprinted with your name or the name of 
your institution at no extra charge. The cost per bound volume is S40.00 for AARC members 
(with valid membership number) and $80 00 for nonmeinbers. Shipping is included for cus- 
tomers within the U.S. and Canada. 

For a limited time, you may also order the 1987, 1988, and 1989 bound volumes at the 
discount pnce of $30.00 for AARC members and $70.00 for nonmembers. The 1990 Bound 
Volume IS now available for $3500 for AARC members and $75.00 for nonmembers. 
Orders must be prepaid, or include an institutional purchase order, or credit card. 

~l Please send bourid volume lor 1991 at $40/$80 
1 Please send bound volume for 1990 at $35/S75. 
~t Please send bound volume for 1989 at $30/$70. 
~i Cfieck enclosed 3 Purchase order enclosed 

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Participant Responses to Blood 
Gas Proficiency Testing Reports — 

JE Hansen. Chest 1992:101:1240. 

There is scant objective information 
regarding the effect of proficiency 
testing for blood gases or other ana- 
lytes on characterizing poor or good 
performers or changing laboratory 
behavior. Following the institution of 
a percentile ranking system for par- 
ticipants in the American Thoracic 
Society-California Thoracic Society 
Blood Gas Proficiency Testing Pro- 
grams, a telephone survey disclosed 
characteristics of three equally sized 
groups of participants as follows: ( I ) 
FAIL (failed rating): (2) LOW (low- 
est percentile rankings without a 

failed rating); and (3) HIGH (highest 
percentile rankings). The FAIL and 
LOW groups often had isolated 
instruments, instruments which were 
infrequently operated, and/or instru- 
ments operated by nontechnicians. 
whereas these characteristics were 
not found in the HIGH group. Those 
in the LOW group who understood 
their ranking and those in the FAIL 
group always found defects or errors 
and took some corrective action. 
This study appears to show that it is 
harder to maintain good performance 
with isolated, underutilized, or non- 
technician-operated blood gas instru- 
ments, and blood gas proficiency 
testing is economical and valuable in 
assessing performance and changing 




Transtracheal 0\yj;en, Nasal 
CPAP and Nasal ()\yj;t'n in Five 
Patients with Ohstructive Sleep 
Apnea — RJ Farney. JM Walker. JC 
Elmer. VA Viscomi. RJ Ord. Chest 

The effect of transtracheal oxygen 
administration by means of a 9- 
French {2.7-mm) percutaneous cath- 
eter was assessed in five patients 
with severe obstructive sleep apnea. 
We hypothesized that the delivery of 
oxygen below the site of airway 
obstruction should reduce the arterial 
oxygen desaturation during apneas 
and hypopneas, thereby increasing 
respiratory stability. Standard sleep 
and respiratory measurements were 
recorded in these subjects with all- 
night polysomnograph) on non- 
consecutive nights during 4 experi- 
mental conditions: room air (BL), 
nasal continuous positive airway 
pressure (CPAP). nasal O: (NC O:). 
and transtracheal O2 (TT O;). In 3 of 
these subjects, room air was infused 
(TT RA) at flowrates comparable to 
TT O:. Compared with baseline 
room air measurements. TT O: not 
only significantly increased the SaO; 
nadir from 10A7c to 89.7% 
(p < 0.01 ). but it also reduced the fre- 
quency of sleep apnea/hypopnea 
from 64.6 to 26.2/h sleep (p < 0.01 ). 
NC O: ameliorated desaturation dur- 
ing apnea/hypopnea (mean S,,o; 
nadir, 86.2%; p<0.01) but did not 
significantly alter frequency (59.0/h 
sleep). Nasal CPAP was the most 
effective means of reducing sleep 
apnea/hypopnea (1.3.8/h sleep) but 
did not abolish dcsaturations when 
apneas occurred (mean S.,o: nadir. 
80.0%). Compared with oxygen, 
transtracheal infusion of room air 
appeared to be somewhat effectixe; 
Imwcvcr. the small number of siLulies 
with IT RA precluded statistical 
analysis. We believe that TT (); is 
superior to NC O2 for some patients 
with obstructive sleep apnea because 
continuous oxygen flow below the 

site of airway obstruction more reli- 
ably prevents alveolar hypoxia and 
respiration is stabilized. Infusion of 
air or oxygen through the tracheal 
catheter flow may also increase 
mean airway pressure and reduce 
obstructive apnea similar to nasal 
CPAP. We conclude that TT O: may 
be an effective alternative mode of 
therapy for some patients with severe 
sleep apnea/hypopnea when nasal 
CPAP is not tolerated or when com- 
bined oxygen and nasal CPAP are 

The Role of Fiberoptic Bron- 
choscopy for Diagnosis of Pul- 
monary Tuberculosis in Patients at 
Risk for AIDS— AM Miro. E Gib- 
ilara. S Powell. SL Kamholz. Chest 

In patients with acquired immu- 
nodeficiency syndrome (AIDS)- 
associated pulmonary Mycobact- 
erium luberculosis (MTB) (Group 
1). we analyzed whether the addition 
of transbronchial biopsy (TBB) and 
bronchial brushings augmented the 
diagnostic MTB yield over non- 
biopsy sampling. Positive acid-fast 
bacilli (AFB) smears from combined 
sputum. bronchoalveolar lavage 
(BAL). and washings were 30% 
compared with 37% when brushings 
and TBB were added (p = NS). The 
addition of TBB increased culture 
yield from 96% to 100% (p = NS). 
Similar results were seen in patients 
with pulmonary MTB without 
human immunodeficiency \irus 
(HIV) risk factors (Group 2). Group 
I patients most ciimmonly had a 
nonspecific innammation on TBB 
histopathology and had a lower inci- 
dence of granuloma formation than 
Group 2 (p<0.0.'^). Our results sug- 
gest thai more invasive sampling 
with bronchial brushings and TBB 
does not contribute to the micro- 
scopic, bacteriologic. or histopatho- 
logic diagnosis of pulnu>nary MTB. 
independent of AIDS risk factors. 

Thcophylline-Induccd Behavior 
Change in Children: .\n Objective 
Kvaluation of Parents" Per- 
ceptions — B Bender. H Milgrom. 
JAMA 1992;267:2621. 

OBJECTIVE: To evaluate children 
who take theophylline for the pres- 
ence of behavioral side effects and to 
determine whether the beliefs about 
these side effects held by their par- 
ents are supported by their own 
observations. DESIGN: A double- 
blind, placebo-controlled, random- 
ized, crossover protocol. Under both 
study conditions the children com- 
pleted tests that measured their atten- 
tion, impulsivity. memory, activity 
le\el. and mood, while the parents 
rated their beha\ior. PATIENTS: 
The subjects were 8- to 12-year-old 
children with asthma whose parents 
had observed ad\erse beha\ ioral side 
effects while the children were tak- 
ing theophylline. Among cited side 
effects were impulsivity. hyper- 
activity, altered mood, and impaired 
attention. RESULTS: No differ- 
ences related to treatment could be 
detected from the parent ques- 
tionnaires or from 6 of 9 scores of 
the psychological e\alution of the 
children. The children, however, 
made fewer attention errors and 
showed a mild increase in anxiety 
and hand tremor of the dominant 
hand while they were recei\ing theo- 
ph\lline. All mean changes were 
small. No significant relationship 
was t'ound between theoph\ Uinc con- 
centrations in the serum and degree 
of change in mood or attention. 
F.le\cn of 42 participants were dis- 
qualified tor nonconipliancc during 
the study. CONCLUSION: Parental 
beliefs about the side effects expe- 
rienced b\ their children are not sup- 
ported by their own observations per- 
formed through a blinded protocol. 
These results are in contlict with 
reports of a high incidence of 
adverse bcha\ ioral side effects attrib- 
uted to theophylline therapy. 


RESPIRATORY CARE • Jl'I.'^' "92 Vol 37 No 7 

Respiratory Care Magazine, 
lanuary 1992,Vol. 37. No. 1. 

'* Blender 

60 70 

50 I / 


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Transcutaneous Oxygen Pressure 
Measurements: A Useful Tech- 
nique to Appreciate the Oxygen 
Delivery to Tissues — FE Wattel DM 
Malhieu. RR Neviere. J Hyperbaric 
Med 1991;6(4):269. 

Tissue hypoxia is a significant factor 
in the risi< of infection and delay in 
healing the process and it is rec- 
ognized that hyperbaric oxygen 
(HBO) increases tissue oxygen pres- 
sures by increasing arterial partial 
pressure. HBO-induced tissue hyper- 
oxygenation has long been accepted, 
but it is essential in clinical practice 
to have means of objectively deter- 
mining the effects actually obtained 
dumg an HBO session. The tech- 
nique for measuring transcutaneous 
oxygen pressures has been shown to 
reflect oxygen delivery to tissues. 
This is a noninvasive method of 
moderate cost and easy to use in 
experienced hands, which seems to 
be of great interest in hyperbaric 
medicine, both for prescribing HBO 
therapy and for monitoring develop- 
ment or evaluating treatment. Exam- 
ples are several pathologic cases of 
peripheral hypoperfusion, such as 
crush syndrome; acute limb ische- 
mias due to arterial trauma: reim- 
plantations of limbs, skin grafts, and 
flaps; arteriosclerotic ulcers; and dia- 
betic foot lesions. Finally, quan- 
tifying peripheral oxygenation defi- 
ciency makes it possible to select 
uniform groups of patients and con- 
sequently carry out randomized clin- 
ical studies that will help to evaluate 
HBO efficiency in comparison with 
con\entional treatment. 

Nosocomial Transmission of 
Tuberculosis in a Hospital I'nit for 
HIV-infected Patients— SW Doo- 
ley. ME Villarino. M Lawrence, L 
Salinas. S Amil. JV Rullan. et al. 
JAMA 1992:267:2632. 

OBJECTIVE: To assess nosocomial 
transmission of tuberculosis (TB). 
DESIGN: A historical cohort study 

of hospitalized patients with the 
human immuodetlciency virus (HIV) 
and a purified protein derivative 
(PPD) tuberculin skin test survey of 
health care workers (HCWs). SET- 
TING: A large public teaching hos- 
pital in San Juan. Puerto Rico. 
P.^TIENTS: For the cohort study, a 
case patient was defined as any 
patient in the HIV unit at the hospital 
who developed culture-positive TB 
from 31 days or more after admis- 
sion through December 31. 1989. 
For the PPD survey, of 1 .420 HCWs 
from the hospital, 908 agreed to par- 
ticipate and had sufficient data for 
URES: For the cohort study, to com- 
pare the risk of developing acti\e TB 
among patients who were exposed to 
hospital roommates with infectious 
TB and the risk among nonexposed 
patients. For the HCW PPD survey, 
to determine the prevalence of and 
risk factors for tuberculous infection. 
RESULTS: 8 of 48 (9.7/10,000 per- 
son-days) exposed case patients vs 4 
of 192 (0.8/10.000 person-days) non- 
exposed case patients developed 
active TB (relative risk [RR1=II; 
95% confidence inten-al [CI] 2.3. 
50.3). Positive PPDs (> 10 mm of 
induration) in HCWs were associated 
with older age (p = 0.0001 ) and with 
history of community TB exposure 
(p = 0.0002). In a multivariate 
logistic model that adjusted for these 
variables, HIV-unit nurses (9 of 19) 
and nurses in the internal medicine 
ward (45 of 90) had a higher pro- 
portion of positive PPDs than the ref- 
erence group (clerical personnel on 
other floors: 35 of 188. p = 0.005). 
CONCLUSIONS: These data sug- 
gest that patient-to-patient trans- 
mission of TB in HIV units can 
occur and that HCWs are at risk of 
acquiring TB infection. 

Ultrathin Fiberoptic Broncho- 
scopy for .Airway Toilet in Neona- 
tal I*ulmonar) .Atelectasis — ES Shin- 
well. Pcdialr Pulmonol 1992:13:48. 

SUMM.ARY: Pulmonary atelectasis 
is often seen in young infants with 
respiratory disease and it may con- 
tribute to increased ventilatory 
requirements and the development of 
chronic lung disease such as bron- 
chopulmonary dysplasia. Standard 
management consists of postural 
drainage (chest physiotherapy and 
suction) and selective intubation w ith 
suction of a major bronchus. This 
report describes a new approach con- 
sisting of removal of bronchial secre- 
tions under direct \ ision \ ia ultrathin 
fiberoptic bronchoscopy, without 
interruption of mechanical ventila- 
tion. The procedure was performed 
safely in 10 cases and resulted in sig- 
nificant rapid improvement in the 
infants' respiratory condition and in 
complete resolution of the atelectasis 
in 8 cases. In 2 infants, partial 
improvement was seen. No adverse 
effects of the procedure were 
encountered. It is concluded that this 
approach is a safe and polcntialh 
valuable therapeutic maneuver in the 
management of pulmonarv atelecta- 
sis in sick intubated neonates. 

A Radiographic Method for F.sti- 
mating Lung N'olumes In Sick 
Infants — MH Fumey, EG Nicker- 
son, M Birch. R McCrea. LC Kao. 
Pediatr Pulmonol 1992:13:42. 

SUMM.ARY: Estimation of lung vol- 
umes by conventional methods in 
sick infants is technicallv diftlcult 
and is the subject of controversy. In 
this study, we compared both tho- 
racic gas volume (TGV), measured 
with an infant whole bodv plc- 
thysmograph. and functional residual 
capacity (FRC). determined bv the 
nitrogen washout technique, to plan- 
imetric measurements of antero- 
posterior chest radiographs in 26 
infants with hronchopulinonarv dys- 
plasia (BPD). The tidal volume (TV) 
of each patient was added to TGV 
and FRC because these were meas- 
ured at the end of expiration w hereas 



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chest radiographs were taken at the 
end of spontaneous inspiration. The 
regression equations expressing the 
relationships between TGV and right 
+ left lung field areas |A + B|. and 
between FRC and lung areas are 
expressed as follows: (TGV + TV| 
(mL) = 3.3 mL/cm= x [A + B] 
cm= + 24 mL and [FRC + TV] 
(mL) = 3.5 niL/cni' x [A + BJ cm- - 
13.5 mL. Correlation coefficients of 
0.9 and 0.7 for TGV and FRC, 
respectively, suggest a stronger cor- 
relation between TGV and lung areas 
than between FRC and lung areas. 
Lung areas measured by planimetry 
correlate closely with physiological 
measurement of lung volumes. We 
conclude that the planimetric method 
is an inexpensive and reliable tech- 
nique for estimating lung volumes in 
young infants with BPD when chest 
radiographs are available. 

Nonbronchoscopic Approach to 
Bronchoalvcolar Lavage in Chil- 
dren with Artificial Airways — BE 

Alpert. BP O'Sullivan. HB Panitch. 
Pediatr Pulmonol 1992:13:38. 

SUMMARY: Bronchoalvcolar lav- 
age (BAD performed with a fib- 
eroptic bronchoscope (FOB) is a use- 
ful method for sampling alveolar 
contents. Since the smallest FOB 
with a channel has a diameter of 3.6 
mm. BAL is difficult to accomplish 
through artificial airways (AA) < 
5.0-mm ID. We used a 4-Fr balloon 
wedge pressure catheter to perform 
BAL through small AA. Supple- 
mental O2 or ventilatory support was 
delivered via an adapter through 
which the catheter was introduced. 
After it was passed distal to the AA, 
the balloon was inflated with normal 
saline (NS) to a predetermined vol- 
ume, and advanced until resistance 
was felt. The balloon was deflated, 
advanced slightly, and then rein- 
flated to achieve airway occlusion. 
Five aliquots of 0.75 mL/kg of NS 

were used for BAL. The procedure 
was performed in 20 children from 1 
month (950 g) to 6.5 years of age 
(median M mo). All specimens con- 
tained abundant alveolar macro- 
phages, indicating good recovery of 
alveolar contents. Clinically sig- 
nificant information was obtained in 
17 (859^) cases, and no patient 
required an open lung biopsy. In con- 
clusion, nonbronchoscopic bron- 
choalvcolar lavage is a valuable 
method for obtaining alveolar con- 
tents in children with small AA that 
preclude the use of an FOB, and it 
obviates the need for open lung 
biopsy in many patients. This tech- 
nique could be used as a research 
tool for measuring constituents of 
alveolar contents in infants and small 

Prediction of the Acute Response 
to Surfactant Therapy by Pul- 
monary Function Testing — MA 

Wallenbrock, KC Sekar, PL Toubas. 
Pediatr Pulmonol 1992:13:11. 

SUMMARY: We tested the hypoth- 
esis that pretreatment pulmonary 
function values would be predictive 
of the response to the synthetic pul- 
monary surfactant, Exosurf® (Bur- 
roughs Wellcome Co) treatment of 
infants with respiratory distress syn- 
drome (RDS). Pulmonary com- 
pliance and resistance were meas- 
ured prior to Exosurf treatment in 40 
infants with severe RDS. In 36 
patients who survived for at least 24 
h the acute response to therapy was 
quantitated by calculated post- 
treatment/pretreatment ratios of ven- 
tilator efficiency index (VEI) and 
arterial/alveolar oxygen tension 
ratios (Pa02/PA02). The values of 
these calculated response ratios 24 
and 48 h after treatment varied 
widely among individual patients. 
The magnitude of the response was 
not related to birthweight, gestational 
age, age at treatment, pretreatment 

VEI, pretreatment Pa():/PA02, or pre- 
treatment pulmonary compliance. 
However, the response to Exosurf as 
measured by improvments in Pa02'' 
Pao2 at 24 and 48 h was related to 
pretreatment pulmonary resistance 
(r = -0.34, p < 0.05 and r = -0.60, 
p< 0.001), high pretreatment pul- 
monary resistance was associated 
with a poor response to Exosurf 24 
and 48 h after treatment. 

The Penlon Oxford Ventilator: A 
Second Look — B Youn, R House- 
knecht. J Hyperbaric Med 1991:6(4): 


The Penlon Oxford ventilator is a 
commonly used ventilator in the 
multiplace chamber. This ventilator 
is a compact, volume-cycled, pneu- 
matically driven, control mode ven- 
tilator that has been proven to be safe 
to 31 atm abs. Many patients have 
severely altered pulmonary mechan- 
ics such as pneumonia, obstructive 
lung disease, and adult respiratory 
distress syndrome. These changes in 
pulmonary compliance and resis- 
tance may significantly affect the 
function of the Penlon ventilator. 
The Penlon was tested serially from 
surface to 6 atm abs with a test lung 
set on various compliance and resis- 
tive settings which were recorded on 
an 8-channel Hewlett Packard strip- 
chart recorder. Measurements 
included fiow, volume, and pressure 
(proximal, machine, and intra- 
pleural). Flow, pressure, and res- 
piratory rate changes were dependent 
on depth, resistance, compliance, and 
machine working pressure. Intrinsic 
positive end-expiratory pressure 
developed as a function of increasing 
resistance, suboptimal I-E ratios, and 
increasing respiratory rate. Aware- 
ness of these changes is important to 
optimize ventilator function and 
reduce potential iatrogenic complica- 



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NIK makes the implementation and 
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Dear Reader: 


1 1030 Abies Lane, Dallas, TX 75229. 214/243-7772. Fax 214/484-2720 

The American Association for Respiratory Care and its science 
journal Rjispiratqry Cake are proud to present the June and July 
1992 issues containing the proceedings from the 1991 Journal 
Conference. The Conference dealt with topic important to all of 
us — emergency respiratory care. The papers and discussions 
presented here are well-organized, state-of-the-art materials 
designed for you to use in your daily practice. 

Considerable planning and work are required to present and 
publish the proceedings of a conference like this. We are grateful 
to the speakers, the Editorial Board, Conference Co-Chairmen 
Thomas A Barnes EdD RRT and Charles G Durbin Jr MD, Editor 
Pat Brougher, and Editorial Coordinator Donna Stephens for 
planning, writing, editing, and participating in the Conference and 
sharing this important information with us. 

We are also indebted to Allen 8e Hanburys, Division of Glaxo Inc, 
for their generous grant to the Association, which made possible 
the presentation and publication of the Conference proceedings. 
Allen &■ Hanburys has supported the last four Journal Conferences 
and for this we will always be thankful. 


Ray Masferrer RRT 
Managing Editor 

Conference Proceedings 

Emergency Ventilation Techniques and Related Equipment 

riioinas A Barnes EdD RRT 


Four major emergenc\ \entilation techniques are 
commonly used duriuL; cardiopulmonary resus- 
citation (CPR): mouth lo mouth (MO-MO), mouth 
to mask (MO-mask), bag and valve to mask or 
tube, and oxygen-powered resuscitator to mask or 
tube. Performance criteria for these techniques and 
related equipment have been published by the 
American Society for Testing and Materials 
(ASTM).' the International Organization for Stan- 
dardization (ISO).- and the American Heart Asso- 
ciation (AHA).' Table 1 li.sts the source of pub- 
lished standards commonly used to evaluate 
emergency ventilation techniques and related 
equipment. In this paper. I review the specifica- 
tions that are considered especially important dur- 
ing CPR. discuss the advantages and disadvantages 
of each technique, and offer recommendations for 
appropriate use of related equipinent. 

Bag- Valve Devices 

The precursor to the first bag-valve device was a 
bellows-valve-mask resuscitator (Fig. 1 ) developed 
by Kreiselman in 1943. which had a bellows vol- 
ume of 1.600 mL. a nonrebreathing valve, and 
valves for pressure release (20 toir). air. and oxy- 
gen intake."* Lucas et al^ described a similar bel- 

Dr Bames is Director of Clinical Education for Respiratory 
Therapy, Director of Cardiovascular Technology, and Asso- 
ciate Professor. Department of Cardiopulmonary Sciences, 
Northeastern University. Boston. Massachusetts, 

A version of this paper was presented by Dr Bames on Octo- 
ber 4. 1991. during the RESPIRATORY Care Journal Confer- 
ence on Emergency Respiratory Care held in Cancun. Mexico. 

Reprints: Dr Thomas Bames. Department of Cardiopulmonary 
Sciences — 206 Mugar. Northeastern University. 360 Hunting- 
ton Ave. Boston MA 02 11 5. 

Fig. 1. A simple tnanual resuscitator invented by Joseph 
Kreiselman in 1943.-' 

lows- valve-mask developed by Trotman in 1951 at 
the British Chemical Defense Experimental Estab- 
lishment. In that description. Lucas et al" reported 
"this device has been thoroughly tested during the 
last eight years, both experimentally and clinically, 
on a large number of unconscious subjects in Ser- 
vice and civilian hospitals under widely varying 
climatic conditions, from the Arctic to the tropics, 
and has been found to be entirely satisfactory." The 
Trotman manual resuscitator (Figs. 2 A & 28"^) had 
a nonrebreathing \al\e and pressure-release mech- 
anism but no provision for adding oxygen to the 
bellows. Six months later. Ruben reported a new 
apparatus for artificial ventilation consisting of a 
"bag and mask coinmonly used in anaesthesia but 
operable without a cylinder."'' Expansion of the bag 
was obtained by lining the inside with foam rubber. 
Ruben claimed that "on occasion the resuscitator 
has been used for more than eight hours without 




Table 1 . Commonly Used Standards for Evaluating Emergency Ventilation Techniques and Related Equipment 






American Heart Association 

American Society for Testing 
and Materials I ASTM)- 

Standards and Guidelines for 1986 

Cardiopulmonary Resuscitation (CPR) and 
Emergency Cardiac Care (ECC) 

Minimum Performance and Safety 1985 

Requirements for Resuscitators Intended 
for Use with Humans (F-920-83) 

This publication is the product of the 1985 
National Conference on Cardiopulmonary 
Resuscitation and Emergency Cardiac Care. 

This specification is under the jurisdiction of 
ASTM Committee F-29 on Anesthetic and 
Respiratory Equipment and is the direct 
responsibility of Subcommittee F29.03 on 
Ventilators and Ancillarv Devices. 

Iiuernational Organization for 
Standardization (ISO)' 

International standard — Resuscitators 1988 

Intended for Use with Humans (ISO 8382) 

ISO is a worldw ide federation of national 
standards bodies (ISO member bodies). ISO 
8382 was prepared by Technical Committee 
ISO/TC 121. Anaesthetic and Respiratory 

causing fatigue in the operator." This may have 
been the genesis of the Ambu resuscitator. Thirty- 
two years later the much improved Ambu Marie 3 
still bears a close resemblance to v\hat may have 
been the first self-inflating bag- valve device. 

Four critical performance criteria for bag-valve 
devices during CPR are fractional concentration of 
delivered oxygen (Fdo:). ventilation capability 
(rate and tidal volume), valve performance, and 
shock tolerance. Because bag-valve devices are fre- 
quently used by health care and public safety work- 
ers to provide emergency ventilation under varying 
and sometimes extreme conditions, and because 
those conditions can affect all four performance 
criteria," the ASTM, ISO, and AHA standards call 
for bag-valve devices to operate across a wide tem- 
perature range of -18°C to -(-50°C and a relative 
humidity range from 407c to 95%.'-' 


Both the ISO and ASTM standards specify that 
Fdo: by a bag-valve device should be > 0.85 with 
oxygen reservoir and oxygen flow of \5 L/min.' - 
The AHA recommends' that "the highest possible 
oxygen concentration (100% is preferable) should 
be administered as soon as possible to all patients 
w ith cardiac or respiratory arrest." 

Several investigators have identified bag-valve 
devices for adults that deliver an oxygen concentra- 

tion < 0.85 in subfreezing ambient conditions, w ith 
oxygen < 15 L/min, when the oxygen reservoir is 
poorly designed, and when minute volume exceeds 
oxygen tlovs to the resuscuator.^ '" Tabic 2 sum- 
marizes the literature on the oxygen concentration 
delivered by bag-valve devices. Table 3 summa- 
rizes the ventilation patterns required by the spec- 
ification for Fdo: capability. 

Over the last 28 years, the design of bag-\alve 
devices has maintained the basic elements of a non- 
rebreathing \al\e. self-inflating bag, and oxygen 
reservoir. Manufacturers have modified the design 
of these components to improve safety and perfor- 
mance, and many have marketed inexpensive dis- 

posable models 

In addition to impnnements in 

equipment, more information has been reported on 
how to use manual resuscitators more cffectixely. 
Table 4 lists several operator-controlled variables 
that have been reported in the literature since the 
first self-inflating bag-valve device was marketed 
in the early 1960s. 

Ventilation Performance 

The Standards have separate specifications for 
ventilation performance for adult, child, and infant 
models of bag-valve devices. Table 3 lists the per- 
formance criteria and compares the differences 
among the ASTM. ISO. and AH.A standards. Sev- 
eral studies have reported that it is very difficult to 


RESPIR.'XTORY CARE • JULY '92 Vol 37 No 7 



Fig. 2A. The Trotman bellows-valve-mask resuscitator 
was invented in 1951 and used clinically for over 8 years. 
1 — Rubber face mask: The fit of the mask is achieved by 
a large pneumatic cushion shaped to fit the face. The 
operator adjusts the cushion's inflation by operating the 
small knurled screw on the special metal pressure- 
release plug situation on the left cheek of the mask and 
blowing into the plug. 2 — Patient valve unit: The valve is 
a slightly concave rubber diaphragm with a central cir- 
cular orifice that is closed by a hinged rubber flap. When 
the bellows is compressed, the diaphragm is raised off 
its original seating by the air pressure and seals against 
a larger circular seating on the face mask side of the 
unit, and air passes through a gap around the periphery. 
The inventors claimed that the valve had no backward 
leakage and that the patient could breathe freely while 
the bellows was being filled for the next cycle. 3 — 
Compressible unit with gas-intake valve and a spring- 
loaded 30 cm H20 [3 kPa] pressure-relief valve that whis- 
tled when venting.^ 2B. The Trotman resuscitator in use.^ 

deliver the ().<S-1.2 L tidal \oluine reeommended by 
the AHA for CPR u ilh a bag-valve-inask (BVM) 
unless the patient is intubated (Fig. 3).^''^' Two 
explanations have been given for the low tidal vol- 
ume delixered by BVM devices: (1) operator's ina- 
bility to maintain an adequate mask seal while 
simultaneously maintaining a patent airway and 
squeezing the bag" '"* '" and (2) gastric inflation/-"^"* 
Gastric inflation in adults appears to increase as 
mean inflation pressure approaches 18 to 20 cm 
H20.''-'''* However, resuscitation of asphyxiated 
babies at birth using BVM devices to deliser rapid 
inflations with pressures less than 35 cm H2O 
should not lead to gastric inflation in newborns.'''' 

Seidelin Elling Jesudian Giffen Lawrence Harrison Hess 

Fig. 3. Tidal volume by bag-valve-mask from published 
studies. ^^'''' 

Melker and Banner observed a dramatic increase 
in volume delivered to an adult lung model (Fig. 4) 
in the presence of high airway resistance when 
inspiratory time was lengthened from 0.5 to 2.0 
seconds (Fig. 5)."*- The improvement created by 
lengthening inspiratory time was lost when the 
lung compliance fell below 0.04 L/cm H^O (Fig. 
6).^- Ornato et al""' reported that pulmonary edema 
during resuscitation could cause a drop in compli- 
ance to 0.022 L/cm H^O. with a peak inspiratory 
pressure of 43 ± 8 cm H2O required to deliver a 
tidal \olume of 936 ± 322 mL. 

With two-person BVM ventilation and two-hand 
compression of the bag, Hess and Baran reported a 
tidal volume of 580 mL delivered to a Laerdal 
Recording Resusci-Anne.^'' Other investigators^^"'' 
have reported higher tidal volumes for two-hand 
BVM ventilation but used intubation models with- 
out measured lung impedance. The F.'XTS approach 
(face and thigh squeeze) improves the size of the 




Table 2. Sumniarj' of the Literature on Fractional Delivered Oxygen Concentration Delivered by Bag-Valve Devices 









of Bags 

( Vt X 






Saklad et al* 



500 X 20 




Ambu with tube reservoir 








Ambu without reservoir 

Redick et al'" 




2 Yes, 4 No 




Tw units used tube reservoir 

Garden et al" 



800 X 10 

2 Yes. 6 No 




Two units used tube reservoir 





2 Yes, 13 No 








2 Yes, 1 No 



Three earh Laerdal models 

White etal'-* 



800 X 12 

1 Yes, 4 No 




Laerdal RFB 11— Fdo: of 0.9 




70 X 60 

2 Yes. 2 No 



All four were infant models 





2 Yes, 2 No 




All four were infant models 




600 X 12 

3 Yes. 1 No 




Ambu Mark 2 had cap on air inlet 




800 X 12 

2 Yes, 6 No 




Hope 1 had a Blount adapter 

Garden et al'* 



600 X 12 

3 Yes, 5 No 












Laerdal infant & child models 

Garden et al-" 



600 X 12 





Priano et al-' 



750 X 12 




Fdo: increased by retarding bag 




600 X 12 

1 1 Yes, 5 No 





Fitzmaurice et al-^ 



600 X 12 










4 Yes, 4 No 




Barnes et al-' 



600 X 12 

3 Yes, 1 No 





Barnes et al-" 



600 X 1 2 

4 Yes. 1 No 





Phillips et al-^ 




4 Yes. 1 No 



Test method not described 

Campbell et al-* 







3 reservoir types compared 

Barnes et al-'' 



600 X 12 





All units were disposable 






10, 15 


Atypical Fdo: test method 

Barnes et al" 



600 X 12 




All units were disposable 

Barnes et al" 



600 X 12 





7 withFDO:<0.85at-18°G 

tidal volume delivered with a BVM during 
CPR.-'7.-'8 With the FATS inethod. the rescuer 
kneels with the head of the subject held finnly 
between the knees. The mask is firmly pressed into 
the face with the palm of one hand, while the lin- 
gers of that hand simultaneously lift the mandible 
and hyperextend the neck. The bag is vigorously 
squeezed with the other hand while being pres.sed 
against the thigh. ■* 

The use of a mask that has a soft, air-tilled cush- 
ion around the rim of the mask reduces leaks.^** 
When the appropriate size and type of mask is used 
to ventilate an infant, the size of the bag (infant. 

child, or adult) does not affect the rale or volume 
delivered to the lung.'"' It takes an experienced neo- 
natal practitioner to use a Mapleson Type D anes- 
thesia bag to ventilate an infant. The anesthesia bag 
tends to collapse due to poor mask tit. low source- 
gas flow , and incorrect adjustment of the pressure- 
release valve."'' With inexperienced personnel, the 
best ventilation of infants usualh occurs w hen self- 
intlatable bag-valve devices are used.^' A Maple- 
son Type D anesthesia bag-valve device can be 
used effectively during resuscitation bv practi- 
tioners who use the bag routinely to ventilate neo- 
natal patients.'" 




Table 3. Ventilation Patterns Specified by Standards for Fdo: and Ventilation for Bag-\'al\e Devices 

Ventilation Pattern (mL x 


O; flow 









(cm H:0 • s • L') 



600 X 12 

600 X 12 

800 X 12 





300 X 20 

15/kg X 20 








6-8/kg X 40 






600 X 20 


800 X 12 



Child 1 

300 X 20 

15/kg x20 




Child 2 

70 X 30 

150 X 25 




Infant 1 

70 X 30 


6-8/kg X 40 



Infant 2 






Table 4. 

Summary of the Literature 


Operator-Controlled Performance 


for Bag 







Saklad et al* 


Saklad et al** 












Ziecheck et al" 








Barnes et aP 


Barnes et al-'^ 


Hess et al™ 


Hess et aP' 


Barnes et al-' 




Barnes et al" 


Attachment of tube-I\ pe O; reserv oir 
Oxygen flow to bag-valve device 
High minute volume 
Operator training 
Retarding bag refill 

Small hand size 

Adjustment of bag compression force 

O; reservoir added to Blount adapter of Hope 1 

Bag storage at low ambient temperature 

PEEP and pressure-limiting device 
Overriding pressure-limiting device 
Limiting O: flow to 20 L/min 

Unbridled minute volume 

Two-hand compression of bag 

Two operators for bag-valve mask 

O; flow set to exceed the minute volume 

O: flow >10 L/min 

O: reserv oir type in cold weather 

FdO: > 0.90 w ith .Anibu bag & reservoir 

Fdo: increases with higher O2 flow 

Recommended O: flow > 15 L/min to maintain Fdo: 

Vt delivered may be improved by operator training 

Increased Fdo: occurs: confirmed in 1988 by 
Campbell et al-** 

Affects Vt; confirmed in 1989 by Hess et af 

Adjust compression force for changes in lung 

3 L bag better than 40 in. tube, also confirmed 
importance of refilling time 

Below freezing temperature affects bag-valve 

Important options for bag-valve devices 

May be necessary with high lung impedance 

High O2 flow, above minute volume, may not 

increase Fdo: 
High minute volume may lower Fdo; vvith small 

volume O: reservoir 

Important with high lung impedance to deliver a 
large tidal volume 

Large mask leaks occur with only one operator 

Some bags do not have air intake valve to assure 
adequate bag refill 

Necessary with adult bags for Fdo: > 0.85 at rates 
> 20 cycles/min 

Low temperature affects bag-type O: reservoirs 





Fig. 4. Diagram of model used to study gas distribution 
during ventilation with an unprotected airway. An Emer- 
son Ventilator (A) simulates the rescuer giving artificial 
ventilation: a pneumotachograph (B) records tidal vol- 
ume; a transducer (C) measures peak inflation pressure; 
a test lung (D) simulates the airway and lungs: and a 
Penrose dram (E) simulates the esophagus of a victim. A 
water PEEP exhalation valve (F) is set at levels of pres- 
sure of the lower esophageal sphincter recorded during 
anesthesia. A Collins spirometer (G) measures the vol- 
ume of gas that is diverted to the stomach. A polygraph 
(H) records tidal volume, inspiratory volume, and peak 

The problems caused b\ gastric insufflation 
(gastric dilation, gastric rupture, aspiration pneu- 
monia) and face-mask leaks with prehospital BVM 
\entilation have prompted a great deal of interest in 

Fig. 5. The effect of lengthening inspiratory time (ti) on 
lung inflation (Vl) in the presence of high airway resis- 
tance (55 cm HsO • s ■ L '). Tidal volume was set at 0.8 
L, esophageal opening pressure at 20 cm H2O, and lung 
compliance at 0.1 Ucm H2O. A dramatic improvement in 
Vl occurred when t, was lengthened from 0.5 to 2.0.''' 

intubation of the airway during CPR.''' Three types 
of airways are used in prehospital intubation: ( 1 ) 
endotracheal (ET) tube,''*"^' (2) esophageal obtura- 
tor airway (EOA),^'^''' or (3) pharyngeal-tracheal 
lumen airway.*'-'^ Intubation of the trachea pre- 
vents gastric insufflation, and tidal volume deliv- 
ered by a bag-valve device is no longer lost 
through mask leaks. Endotracheal intubation during 
prehospital CPR has been associated signiflcantly 
with improved survival in pulseless nonbreathing 
pediatric patients.'''^ The ET tube is preferred over 
the EOA b\ many as the airway of choice for pre- 
hospital emergency ventilation.'''"''^ 

When one uses a bag-valve device to ventilate a 
patient with an endotracheal tube in place, it is dif- 
ficult to deliver a tidal volume of 0.8-1.2 L with 
one-hand compression of the bag. The following 
one-hand tidal volumes have been reported at a 
compliance of 0.02 L/cm H^O and resistance of 20- 
28 cm H:0 • s • L': ECRI 660 mL.'" Hess and 
Goff .S.SO mL,™ and Van Hooser 546 mL'' (Fig. 7). 
At the same high lung impedance, a two-hand 
squeeze of the bag results in a tidal volume of 800- 
900 mL.™-'- At normal lung impedance with a 7- to 
8-mm ET tube, a one-hand squeeze of the bag 
delivers only 600 mL and a two-hand squeeze pro- 
vides 900-1.000 niL.™-'-'-'-' Practitioners with small 
hands, as a group, tend to deliver 100-250 mL less 
w ith a one-hand squeeze of the bag than those with 
large hands. - ' In order to ventilate during CPR 
with the tidal \olume recommended by the AHA. 
most practitioners will need to use two hands to 
squeeze the bag. Using volumetric feedback to 
teach staff members how to best use bag-\al\e 
devices has been shtivsn to improve the tidal \ol- 
umes delivered.^" I believe that this type of instruc- 
tion should be given to all health care personnel 
involved in resuscitation. 

Bag- Valve \'entilation of 
Children and Infants 

The Standards for bag-valve devices used with 
children and infants require a pressure-relief valve 
to limit peak inspiratory pressure (PIP).' 'This so- 
called pop-off valve (POV) must provide an aud- 
ible signal that gas is being vented, a mechanism 
for overriding the POV. and a visual indicator of 
when the POV is operative or inoperative. The 


RESPIRATORS' CARH • JULY "92 Vol .^7 No 7 










■/" r 

1 0.08 0.06 0.04 0.02 

Cl (L/cm H2O) 

1 1 1 1 

0.1 0.08 0.06 0.04 0.02 

Cl (L/cm HjO) 

Fig. 6. Compliance volume curves at inspiratory times of 0.5 s (■), 1.0 s (•), and 1.5 s (*) with esophageal opening pres- 
sure set at 20 cm H20.''2 



Van Hooser 

Fig. 7. Tidal volumes by bag-valve and endotracheal 
tube using one-hand compression with a lung analog set 
at a compliance of 0.020 Ucm H2O and resistance of 20- 
28 cm H2O ■ s • L ' reported by ECRI, 3° Hess and Goff,'° 
and Van Hooser et al.' ' High lung impedance lowers the 
tidal volume that can be achieved. The results of these 
three studies should be compared to the minimums rec- 
ommended by the American Heart Association (AHA), 
800 mL, and the American Society for Testing and Mate- 
rials (ASTM),600 mL. 

POV limit required by ASTM Standard F-920 is 40 
± 10 cm H.O for children and 40 ± 5 cm H.O for 
infants' and ISO Standard 8382 specifies that the 
pressure should not exceed 45 cin H^O for neonates 
and infants.- Some POVs have been shown to vent 
gas at pressures varying from 38-106 cm H20.^*'^ 
The venting of gas through the POV reduces the 
Fio: significantly and lowers the tidal volume pro- 
duced by one third to one half of that produced 
when the POV is inoperative.^'' Bag-valve ventila- 
tion by competent practitioners with an in-line 
manometer and without a POV (or with POV inop- 
erative) may be safer for neonates and small chil- 
dren especially for delivery of the first breaths of a 
neonate's nonaerated lung when higher pressures 
may be needed.' ^ The PIP during ventilation with 
a Mapleson Type D bag has been compared to PIP 
during mechanical ventilation. The PIP values 
delivered without a manometer were significantly 
higher than those delivered with a manometer.''' 




Practitioners using pressure manometers to mon- 
itor PIP during infant bag-valve ventilation need to 
assure that the manometer is accurate at rates 
greater than 4()/min because some manometers 
underestimate the actual pressure.**" As an alter- 
native to pressure-monitored bag-valve ventilation, 
a neonatal volume-controlled resuscitator has been 
developed (Fig. 8).^' Preliminary studies of the pro- 
tot\pe suggest that the device is capable of pro- 
\idmg adequate ventilation at mean airway pres- 
sures lower than those observed with pressure- 
monitored bags. **'■**- Lung rupture in ihc newborn 
infant has been reported at a relati\ely low PIP of 
35 cm H2O. suggesting that bag-valve ventilation 
cannot be regulated rationally by looking at airway 
pressure or deli\ered tidal volume alone but must 

include observation of chest movement and blood 
gas analysis.**'-'"*'* 

Resuscitation of newborns at birth often 
involves BVM ventilation, and if correctly admin- 
istered spares the infant from the possible hazards 
associated with intubation. ''^"^'' The critical com- 
ponents for effective use include a self-expanding 
bag of suitable volume to compensate for face- 
mask leaks, properly functioning nonrebrcathing 
and pressure-limiting valves, and a circular face 
mask. A hard moulded mask (Rendell-Baker) 
should not be used to ventilate newborns it 
docs not easily fit the contours of the baby's face 
and leakage occurs. *''' Peak pressure was less than 
809^ of the opening pressure in 579c of the trials 
u hen a Rendell-Baker mask was used to ventilate a 

^^^^ . _ 

" ■■f m iiii^ii J ^».^i..L»^». 

•e- — 









Fig 8. Schematic of the volume-controlled device for neonatal manual resuscitation. 1 — Gas inflow reservoir box. 2 — one- 
way gas-intake valve, 3 — pressure chamber, 4 — reservoir box gas outflow valve, 5 — fixed graduated cylinder, 6-small 
holes that perforate graduated cylinder, 7 — plunger-type platform for volume adjustment, 8 — handle for volume adjustment 
plunger, 9 — inflatable latex balloon, 10 — squeeze bag, 11 — tube connecting bag to latex balloon, 12 — patient circuit, 13 — 
patient valve with adjustable PEEP, 14 — adjustable pressure-release valve, 15 — pressure manometer, and 16— adjustable 
PEEP control."' 


RH.SPIRA rOR't CARE • JULY '92 Vol 37 No 7 


1- to 2-day-old newborn, but less than 807f of 
opening pressure in only 4'} when a soft eircular 
mask was used/'' Problems related to creating a 
seal with a mask may require tracheal intubation 
for resuscitation at birth. None of the initial three 
inflations delivered by BVM in a series of 200 
resuscitations at birth (no breathing after 1 minute) 
were adequate (4,4 mL/kg body weight), whereas 
379f of the tidal volumes deli\ered to intubated 
infants met the criteria. "" A prolonged and slow- 
rise inflation (3-5 s) in the resuscitation of the 
asphyxiated newborn infant has been reported to be 
more effective in producing a larger inflation vol- 
ume than that seen during conventional 1 -second 
square-wa\e inflation."' Healthy full-term neonates 
at birth rarely show an inspiratory opening pressure 
of more than 10 cm H^O.''" However, some infants, 
particularly premature infants'^' and babies bom by 
cesarean section.''"' may need ventilating pressures 
greater than 30 cm H.O before they respond to 
resuscitation. Very low lung compliance of 0.3 mL/ 
cm HjO has been reported in a premature infant at 
birth, w ith an increase to only 0.6 niL/cm H2O after 
1 minute.'*' The operator must be able to inactuate 
the POV on a self-inflating bag- valve device to 
adequately ventilate infants with very low com- 
pliance. Preterm infants with respiratory distress 
syndrome may react differently to BVM \entila- 
tion. In those infants who remain quiet during 
BVM ventilation, the transcutaneous partial pres- 
sure of oxygen (PicO:) has been observed to 
increase for up to 20 minutes; whereas in those 
infants who are restless, a decrease in PicO: for up 
to 20 minutes has been observed.''^ Consequently, 
bag-valve ventilation should be discontinued when 
an infant becomes restless. 

BVM ventilation is frequently used in the man- 
agement of infants with respiratory distress syn- 
drome who are on continuous positive airway pres- 
sure (CPAP). The capability of attaching a PEEP 
device to maintain end-expiratory pressure is con- 
sidered to be important for those infants on 
CPAP.^* The BagEasy and Bauman manual resus- 
citators have PEEP capability contained in their 
design (Fig. 9).""" The PEEP on the BagEasy is 
adjustable from 0-15 cm HiO.'*** The Bauman's 
nonrebreathing valve retards exhalation extending 
it up to 6 seconds, but there is no way to maintain a 
specific PEEP level.''** Neonatal practitioners 

skilled in the use of the Mapleson Type D anes- 
thesia bag with a pressure manometer can maintain 
a PEEP le\el by adjustuig the flow-control valve 
and hand position on the bag. A manometer can be 
ct)nnecled to the orifice intended for POV attach- 
ment or to a low-dead-space adapter placed at the 
patient connector.'** 




Fig. 9. The BagEasy (A) and Bauman (B) manual resus- 
citators with PEEP capability contained in their 
design. ^""^^ 

Nonrebreathing Valve Performance 

A nonrebreathing valve (NRV) has been iden- 
tified as a critical component of manual resus- 
citators since their early development."'" An NRV 
should function without jamming in the presence of 
vomitus. across an extreme temperature of-18°C 
to -h50°C. with high flows up to 30 L/min. after 
immersion in water, and after being dropped from 
1 meter onto a concrete floor.'"'' Vomitus and water 
are easily cleared and do not cause NRVs to 


Extreme temperature does not 
affect NRV operation, but may affect cycle rate 
due to changes in bag compliance. -'•^''-^^■" There 
have been two reports of an NRV freezing from 
exhaled condensate under laboratory test condi- 
tions'" '" and one recent report that valve freezing is 




not a prohlem.'"' High source-gas flow has caused 
several models ot NRV lo jam in the inspiratory 
position."-'^--^-'"^"'-^ The modem "duck-bill" type 
NRV does not jam at high flow.-'' '- However, there 
is no advantage gained in setting source-gas flow 
higher than 15 L/min for most adult bag-valve 
devices (10 L/min for small children and infants) 
unless the minute volume required exceeds source- 
gas flow.**" Several bag-val\e devices have failed 
the "drop test," and have had critical components 
made inoperative at 21°C and at the extreme ends 
of the required operating range -18°C and 50°C.-''''- 
Problems with shock tolerance are equally divided 
between disposable and permanent bag-valve 
devices.-''-'- My experience has been that most 
manufacturers strengthen or redesign the com- 
ponent that fails once the problem has been brought 
to their attention. 

Bag-\al\e devices are required by the .Standards to 
prevent backward leakage of exhaled gas into the 
bag.'- The Samson neonatal newborn resuscitator has 
no NRV, and significant rebreathing occurs if it is 
used for any purpose other than establishing func- 
tional residual capacity at birth."""""' The ball- 
valve NRV may also cause clinically important 
rebreathing of CO. to occur.-'- '"-'*■""' Forward leak 
through the NRV can decrease the capability of an 
infant manual resuscitator with small bag to deliver 
adequate tidal volume. Forward leak has been 
observed on child and adult bag-valve devices, but 
it may not be a clinically important problem 
because the larger squeeze bag of these models has 
adequate volume to compensate for the leakage. 
However. BVM ventilation with mask leaks com- 
bined with forward NRV leakage may be a clin- 
ically important problem and should be studied fur- 
ther. Ventilation of intubated patients with high 
lung impedance using one-hand compression of 
bag-valve units with forward leakage has not pre- 
vented adult and child models from passing the 
ASTM and ISO ventilation standards.--'-'"--'''--™ 
However, it may be the reason why some adult 
bag-valve devices cannot meet the AHA standard 
for tidal volume (0.8-1.2 L) when luiii: impedance 

The inspiratory and expirator\ flow resistances 
of the NRV of bag-valve devices are required to be 
< 5 cm H:0 by the ISO 8382 standard.- ASTM and 
ISO both require the operation and maintenance 

manual to state the expiratory resistance.' - Most 
studies on bag-\al\e de\ices ha\e ignored this 
aspect of their performance, and u ork is needed in 
this area."'- 

Mouth-tu-Mask Ventilation 

Emergency ventilation by mouth-to-mouth 
(MO-MO) breathing was successfully used 250 
years ago to resuscitate an apneic and pulseless 
coal miner'"^ and is cited in the Old Testament, II 
Kings.""* In \9^3. an indirect MO-MO method that 
allowed exhaled air ventilation by tube and mask 
was used for newborn resuscitation.'"'' In 1954, 
Elarn and co-workers evaluated mouth-to-mask 
(MO-mask) ventilation on adult patients under gen- 
eral anesthesia and found that the method could 
consistently sustain normal respiratory gas 
exchange.'"^ In 1958. Safar and McMahon reported 
that "during 12 controlled experiments 87 
untrained rescuers performed the mouth-to-airway 
method on anesthetized and curarized adults and 
delivered a tidal volume of 1.000 ml. at a rate of 
I2/min for up to 30 min without getting dizzy" 
(Fig. 10)."" Adequate tidal voUimes were produced 
by the first or second breath after insertion of the 
airway, which took from 5-40 seconds."" A device 
developed at the U.S. Army Chemical Center in 
1959 had a mask, nonrebreathing \al\c (which con- 
tained an air-intake port), and deli\er\ hose with 
mouthpiece (Fig. 11).'" The nonrebreathing valve 
was placed proximal to the mask and 300 mL of 

Fig. 10. A — Insertion of airway: B — mouth-to-airway tech- 
nique; and C — during mouth-to-airway technique note 
position of rescuer's hands. "° 





Fig. 11. A 1959 mouth-to-mask resuscitation device. The 
operator blows the hose contents of 300 mL of fresh air 
into the patient's face. His exhaled air follows. While the 
operator is blowing air, the diaphragm moves away from 
the upper valve seat and allows fresh air to flow through 
holes in the diaphragm through the lower valve housing 
and mask and into the patient's lungs. Simultaneously, 
the diaphragm is pressed onto the lower valve seat, 
which closes the exhalation port. At the end of the oper- 
ator's exhalation, the pressure in the hose drops to zero, 
and the higher pressure in the patient and mask initiates 
exhalation and closes the upper valve seat, preventing 
patient-valve backward leakage and simultaneously 
opening the lower valve and exhalation port. During the 
patient's expiratory phase, the operator inhales through 
the mouthpiece, drawing 300 mL of his own exhaled gas 
from the hose followed by fresh outside air. During the 
last part of the operators inhalation phase, he draws in 
sufficient air to finish filling his lungs and to replace the 
air in the hose with air to be used by the patient during 
the next inhalation. The operator has no face-to-face 
proximity and does not hyperventilate.'"' 

dead space placed between the valve and mouth- 
piece for rebreathing to pre\ent the rescuer from 
hyper\entilating him.self.'" One year later, this 
MO-mask device was used clinically with oxygen 
supplied at the inhalation inlet and permitted resus- 
citation with oxygen supplied from a demand valve 
or continuous-flow system."- Problems encoun- 
tered 25 years ago with BVM devices prompted 
Seeler to embody a MO-mask device into a manual 
resu.scitator (Fig, 12).'" Safar has reported that a 
pocket mask could be used to overcome public 
objection to oral contact with strangers and that it 
allowed freedom of the operator's two hands for 
the "'triple airway maneuver,""'' The pocket mask 
has al:.j been u.sed with oxygen added through a 
nipple during emergency ventilation and with a 

Hond Strop 

Upper Volve 

Control Hopptr 

Squeeze Bog 

300 can. 
Control Tube 

Lower Voke 

Fig. 12. Bag-valve-mask with built-in mouth-mask device 
designed by Henry Seeler in 1966."^ 

nonrebreathing-valve reservoir attached to the 
breathing port for spontaneous inhalation,"' A 
PEEP \ alve attached to the expiratory port of the 
nonrebreathing \alve attached to the breathing port 
of a pocket mask permits spontaneous breathing 

Since 1979. the AHA standard has recom- 
mended that MO-mask ventilation with supple- 
mental oxygen be used until an endotracheal tube 
or esophageal airway can be inserted unless the res- 
cuer has extensive specialized training and demon- 
strated proficiency with BVM devices.''"'' MO- 
mask devices can deliver large tidal volumes to a 
mannequin''''-^''"" "'^ or paralyzed subject.'"^"-"'' 
However, some MO-mask devices deliver less than 
the 800 mL volume recommended by the AHA 
when used on Laerdal Adult Recording Resusci- 
AnneiPig. 13)."' 

BVM devices are used almost exclusively by 
some groups of prehospital and hospital personnel 
for ventilation during CPR.^'' "^ The preference for 

RESPIR.'XTORY CARE • JULY "92 Vol 37 No 7 




4 4 

0.4 0.6 0.8 

Volume (L) 


Fig. 13. Mean volumes delivered by mouth-to-mouth and 
moulh-to-mask ventilation."^ Arrows indicate minimum 
tidal volume recommended by American Society for Test- 
ing and Materals (ASTM) and American Heart Associa- 
tion (AHA). 

the BVM devices may be related to the facts that a 
BVM can deliver a higher Fdo: than MO-mask 
devices, some MO-mask devices require the res- 
cuer's face to be close to the victim (lack of exten- 
sion tube), and an adequate filter may not be pre- 
sent between the mouthpiece and the mask.'"'"'''"* 
However, as early as 1960 MO-mask devices had a 
port for adding oxygen to increase Fdo:,""'"^ and 
at least three designs had an extension tube.'""^ 
However, recent evaluations of MO-mask devices 
have found 50% or more of the devices without 
extension tube or oxygen port."'"" Some MO- 
mask devices when supplied with 15 L/mm of O, 
to a port on the mask can deliver an Fdo: of 0.54 
(ventilation pattern of 12/min x 1.0 L).'" Several 
modifications of MO-mask devices have increased 
the Fuu: possible with 15 L/min O; to > 
O.TO.'"'*""'^"'' Filters arc not provided on several 
currently used MO-mask devices, which combined 
with evidence that some one-way valves leak may 
explain the popularity of BVM devices.^^'"'-"'-' 

The MO-mask devices make it possible to pro- 
vide indirect MO-MO breathing as first suggested 
by Mackenzie in 1933."" They can be used suc- 
cessfully by health care and public service per- 
sonnel and laymen to deliver the AHA recom- 
mended tidal volume.'^""" However, there are 
only a few studies in tiie literature reporting the dis- 

tribution of an 0.8 L breath between the lungs and 
stomach at varying inspiratory times (t, ) and lung 
impedances.''- '-■ Johannigman et al report that gas- 
tric insufflation may be higher with MO-MO and 
MO-mask breathing than with BVM ventila- 
tion.'*"-- At a compliance of 0.02 L/cm H;0 the 
lung volume (Vt.) delivered by MO-MO and MO- dropped significantly below 0.8 L. and the 
gastric volume (Vg) was equal to or higher than 
Vl.'" More work under conditions of varying lung 
impedance needs to be done to clarify the effect of 
ventilation method on inspiratory time, airway 
pressure, V'l, and Vg. 

Mouth-to-Mouth Breathing 

Mouth-to-mouth (MO-MO) breathing has proven 
to be the most reliable wav for health care and public 
service personnel and lavpersons to administer a 
tidal volume of 0.8-I.2' L.^^-^^"""""-"""' The 
AHA has recommended the use of MO-MO breath- 
ing for CPR in its guideline for basic cardiac life 
support (BCLS) since 1974.'-^ Gastric inflation 
with MO-MO appears to be minimal when lung 
impedance is normal.'*-'-- However, the potential 
for gastric inflation increases when upper-airway 
pressure rises as a result of one or more of the fol- 
lowing: short inspiratory time (t,), high airway 
resistance, \o\\ lung compliance, inappropriately 
large tidal volume, and incremental breaths (no 
time allowed for lung dellalion between 
breaths).*- '--•'-"'"'-* Firm pressure on the neck a- 
gainst the thyroid cartilage (Sellick maneuver) has 
long been used by anesthesiologists to prevent 
regurgitation and gastric inflation during positive 
pressure breathing, and cricoid pressure should be 
used during MO-MO when airwav pressure is 
high.'-* '-' Incremental breaths are no longer rec- 
ommended by the .A.HA because more air is likely 
to enter the stomach than the lungs.''" When lung 
impedance is high, a breath should be delivered at 
ti, of 1-1.5 seconds so that inspiratory flow and 
pressure are as low as possible.^ '*-'--'-^ 

.Alternate BCI.S-CPR techniques such as asyn- 
chronous ventilation (.ASV-CPR). which allows a 
longer t,, may result in a larger V^ and smaller 
Vg-'-^"'-'^ Simultaneous compression and ventila- 
tion CPR (SCV-CPR) may decrease the likelihood 
of gastric inflation by delivering a portion of each 




breath with higher than normal intraesophageal 
pressure.'"^"" SCV-CPR may increase carotid 
artery blood tlow ; ho\\e\er. more work needs to be 
done before changes to the AHA guidelines can be 

A major concern since MO-MO was first adopted 
has been whether a rescuer would hesitate to use the 
technique on a stranger based on a fear of contracting 
a disease such as hepatitis B or acquired immuno- 
detlciency syndrome (AIDS).""'"""-"-''""^ A 
recent survey of BCLS instructors found that 40% of 
respondents (comprised of health care and public ser- 
vice personnel and laypersons) would hesitate to do 
MO-MO because of a fear of catching a disease. 
Secondary reasons that ranked high were lack of 
airway equipment and the feeling that their help 
was not needed.'" A 1987 survey of 728 partici- 
pants in a mass AHA Heartsaver CPR training 
course (3.5 hours of instruction to laypersons) 
found that 97% would do CPR on a subject they 
didn't know personally;''*- however, only 44.5% 
would do CPR on a known or suspected AIDS 
patient (this dropped to 32.3% in a follow-up sur- 
vey 6 months later). A 1988 survey of house offi- 
cers from 7 New York City hospitals with large 
AIDS populations found that 48% of medical and 
30% of pediatric house officers reported a moder- 
ate-to-major concern about acquiring AIDS from 
their patients.''*'' An evaluation of 998 out-of- 
hospital bystander resuscitations showed that exter- 
nal chest compression was initiated 82% of the 
time and MO-MO in only 64% of the cases. "^ A 
review of the backgrounds of the bystanders 
showed that MO-MO was done by 76% of family 
members (n = 78) and 61% of physicians 
(n = 592) and that emergency cardiac care was 
done by 84% of physician bystanders."' There 
appears to be a growing concern over providing 
MO-MO to high risk patients as the AIDS epi- 
demic worsens.'"'^-' The AHA guideline for BCLS 
points out that laypersons have only a minimal risk 
because they provide CPR at home (70% to 80% of 
cardiac arrests occur at home) where the health of 
the victim is known.' Health care and public ser- 
vice workers are less likely to know the health 
background of the victim and should follow appro- 
priate measures such as using MO-mask and BVM 

devices, and Universal Precautions when exposure 
to blood or other body fluids is a possibility.' 

The Emergency Cardiac Care Committee of the 
AHA issued a special communication in 1989 
addressing the risk of infection during CPR train- 
ing and rescue."'* This special communication 
made several recommendations regarding the 
appropriate ventilation technique to use with cer- 
tain "high risk" patients or rescuers.'^'* The fol- 
lowing recommendations are germane to ventila- 
tion techniques: ( 1 ) Rescuers who have an 
infection that may be transmitted by blood or saliva 
or believe that they have been exposed to such an 
infection should not perform MO-MO if other 
methods are available (eg, MO-mask or BVM); (2) 
individuals have a duty to respond to the CPR 
needs of high risk patients using an MO-mask of 
adequate design or BVM device and should be 
trained in their use; and (3) early intubation should 
be encouraged when equipment and trained pro- 
fessionals are available."'' The communication has 
created a great deal of controversy in regard to its 
impact on bystander CPR by laypersons. '''^■'-'^ The 
following questions and comments have been 
raised concerning the special AHA communica- 
tion: ( 1 ) Will the changes in CPR training increase 
the fear of infectious disease transmission and 
resuh in less bystander CPR? (2) Will the 
responder pool diminish if MO-mask and BVM are 
not available? (3) High risk populations are resus- 
citated by public service workers who already have 
protective devices. (4) No apparent problem exists 
in prehospital CPR. (5) The concern appears to 
reside with CPR instructors only.'"' The trans- 
mission of the human immunodeficiency virus 
(HIV), the etiologic agent of AIDS, is reported to 
occur perinatally. through sexual contact, and after 
exposure to infected blood or blood products."' "'"* 
Although it has been recommended by the AHA 
special communication''''' that MO-MO be replaced 
with MO-mask and BVM for high risk patients, 
there is no evidence that the AIDS virus can sur- 
vive in saliva. '^^"''*' Health care workers are 
reported to be at minimal risk for HIV and HBV 
(hepatitis B virus) transmission from occupational 
exposure to patients with AIDS or ARC (AIDS- 
related complex), even when exposed for pro- 




longed periods of time.'''-'"'^ However, health care 
workers should follow Centers for Disease Control 
(CDC) guidelines for prevention of transmission of 

should be inspected and tested before each tour of 
duty and after each resuscitation, and a more exten- 
sive performance check should be made on a regu- 
lar schedule.'-''-*" 

Oxygen-Fowtred Resustitators 

In Summary 

Performance and safety standards for oxygen- 
powered resuscitators ha\c been established by the 
AST.Vl.' ISO,- and AH.A.' The standards for oxygen- 
powered resuscitators are simihir to those established 
for manual resuscitators and include specifications for 
Fdc)> shock tolerance, inspiraloiy How. \alve per- 
formance, and pressure-limiting capability. The 
demand \al\e and pressure-release system are of 
great concern because of numerous reports of valve 
failure leading to delivery of \ery high pressure (150- 
3,500 cm H:0) to the airway.'*'-' Osbom has 
reported that tleid testing of 60 gas-powered resus- 
citators resulted in a 25% failure rate ( 15/60 units). '■** 
The 15 oxygen-powered resuscitators were defec- 
tive for the following reasons: failure to achieve 
adequate inspiratory pressure, inflation to excessive 
inspiratory pressure (150 to 375 cm H;0), failure 
to allow exhaust during exhalation, and failure to 
achieve adequate flow.''*'' 

When demand valves are used to replace oxygen 
reservoirs on self-inflating bag-val\e de\ices, the 
follow ing problems may occur: ( 1 ) Bag refill time 
is longer and the cycle rate becomes limited. (2) 
Actuation of the demand valve during exhalation 
may apply dangerous levels of PEEP. (3) If the 
demand \alve malfunctions, the inspiratory pres- 
sure may reach 3,500 cm H^O. (4) Some field per- 
sonnel resort to triggering the valve, thus suddenly 
filling the bag under high pressure (demand valves 
with triggers should not be used with self-inllating 
bag-valve devices).-** The potential for complica- 
tions is high with oxygen-powered resuscitators, 
and their use requires extensive training, practice, 
and retraining.'-'-*'''*'-'^ They are not appropriate 
for use with pediatric patients.^ The following 
guidelines have been recommended: ( 1 ) Their use 
should be restricted to intubated patients because of 
the potential for gastric intlation: (2) personnel 
using the resuscitators should be taught how to rec- 
ognize malfunction and to institute bag-valve ven- 
tilation if malfunction t)ccurs; and (3) the units 

Emergency ventilation techniques used during 
CPR have been refined over the last 40 years. The 
methods and equipment for emergency ventilation 
all have their advantages and disadvantages (Table 
5), and the appropriate technique varies with the 
training and experience of the rescuer. Problems 
encountered during CPR with victims who have 
unsecured airways remain unresohed at this time 
and more work needs to be done. Respiratory care 
practitioners because of their special training and 
experience with resuscitation are in an excellent 
position to make contributions to our knowledge by 
implementing and publishing relevant clinical stud- 


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135. Fluck RR, Sorbello JG. Mouth-to-nioulh resuscitation 

by lay rescuers — should they or shouldn't they? (point 146. 

of view). RespirCare 1990:35:831-832. 

136. Durbin CO. Mouth-to-mask resuscitation by lay res- 
cuers — will they or won't they? (point of view). Respir 147. 
Care 1990:35:832-834. 

137. Lifson .AR. Do alternative modes for transmission of 148. 
human immunodeficiency virus exist? JAMA 1988:259: 
1353-1356. 149. 

138. Friedland GH. Klein RS. Transmission of the human 
immunodeficiency virus. N HngI J Med 1987:317:1 125- 150. 
1 1 36. 

139. Groopman JE. Salahuddin SZ, Samgadharan MG. 151. 
Markham PD, Gonda M. Sliski A, et al. HTLV-Ill virus 

in saliva of people with AlDS-related complex and 
healthy homosexual men at risk for AIDS. Science 

Ho DD. Byington RE. Schooley RT. Flynn T. Rota TR. 
Hirsch MS. Infrequency of isolation of HTLV-III \ irus 
from saliva in AIDS (letter). N Engl J Med 1985:313: 

Fox PC. Wolff A. Yeh CK, Atkinson JC. Baum BJ 
Saliva inhibits HIV- 1 infecti\it\. J .Am Dent .Assoc 
1988:1 16:635-637. 

Gerberding JL. Bryanl-LeBlanc CE. Nelson K. Moss 
.AR. Osmond D. Chambers HF. et al. Risk of trans- 
mitting the human immunodeficiency virus, cytomega- 
lovirus and hepatitis B virus to health care workers 
exposed to patients with AlDS-related conditions. J 
Infect Dis 1987:156:1-8. 

Saviteer SM. White GC. Cohen MS. IITLV 111 exposure 
during cardiopulmonary resuscitation. N Engl J Med 

Centers for Disease Control. Recommendations for pre- 
vention of HIV transmission in health-care settings. 
MMWR l987:36(Suppl):3S-18S. 

Centers for Disease Control. Guidelines for prevention 
of transmission of human immunodeficiency virus and 
hepatitis B virus, and other blood borne pathogens in 
health-care settings. MMWR 1988:37:377-382.387-388. 
Osborn HH. Kayen D. Home H. Bray W. Excess ven- 
tilation with oxygen-powered resuscilators. Am J Emerg 
Med 1984:2:408-413. 

ECRI. Hazard: demand valve resuscitators. Health 
Devices 1976:5:145-146. 

Pradis IL. Caldwell EJ. Traumatic pncumocephalus: a 
hazard of resuscitators. J Trauma 1979:19:61-63. 
ECRI. Evaluation: oxygen-powered resuscitators. 
Health Devices 1974:3:207-221. 

ECRI. Evaluation: gas-powered resuscitators. Health 
Devices 1978:8:24-38. 

Fasi TH. Lucas BG. An ev aluation of some mechanical 
resuscitators for use in the ambulance service. Ann R 
Coll Surt: EnsI 1980:62:291-293. 

Barnes Discu.ssion 

Nemiroff: A subset of near-drovvniiig; 
that I presented consisted of bridge 
jumpers, and I neglected to say that 
859f were HIV-positive or had AIDS. 
This population was literally thrust 
on young emergency medical tech- 
nicians. Our experience very much 
matched yours. Once emergency per- 
sonnel had been prov ided with appro- 
priate barrier techniques, there was 
100% compliance with performing 
bag-valve-mouth and mouth-to- 
device type of resuscitation (personal 
communication. EMI R Martin, 

usee Station. Golden Gate. Cal- 

Barnes: That's a good point. 1 think 
It's really important to find mouth-to- 
mask devices that have filters and 
extension tubes. If you expect them 
to be used, you have to decrease the 
face-to-face pro.ximity. and you have 
to give the staff some assurance that 
the valve and the filter really are 

Jeffs: 1 have a question about the 
bags themselves — a Iloppy bag at the 
back as a reservoir versus a tube. Do 
you know of studies or have you 
done studies addressing the refill of 

the actual resuscitation bag'.' We 
have found that the Iloppy bags 
(unless you hook them up to oxygen 
or some other How device) cause 
such a resistance to the refill o\' the 
bag you're trying to ventilate with 
that it's actually dangerous. 
Barnes: I think that's probably true. 
I haven't done studies that have 
looked at that particularly, but that 
would be true if there's no t)ther air 
intake valve (like the Laerdal. for 
instance). That's particularly a prob- 
lem with some of the new dis- 
posable bags that may not have an 


RESPIRATORY CARIi • JL'LY '92 Vol 37 No 7 


emergency air intake valve on the 
back of them. It could restrict refill. 
Branson: You kind of skipped over a 
paper that Jay Johannigman and our 
group published in the Journal of 
Trauma J How do you think we ought 
to ventilate the patient out of hospital 
(CPR by paramedics)? Should we use 
mouth-to-mask? Enough studies have 
been done at this point to establish 
that bag-valve-mask just is not appro- 
priate with one person. We have to 
have another technique. What is it 
going to be? 

1. Johannigman JA, Branson RD. Davis 
K, Hurst JM. Techniques of emer- 
gency ventilation: a model to evaluate 
tidal volume, airway pressure, and 
gastric insufflation. J Trauma \99\: 

Barnes: Well, I think there's a lot to 
be said for early intubation, and as 
was pointed out by Bob (Kacmarek), 
several series show that the intuba- 
tion success rate by EMTs is 90 or 
95%.''' So, if they have that skill, 
that's going to be the best way to 
assure that you don't have gastric 
insufflation and will be able to 
deliver an adequate volume and per- 
haps use two hands. I agree that 
doing bag-valve-mask ventilation is 
difficult, and it really can't be done 
unless the person's trained in the 
technique. They also have to use the 
technique that Cummins is using,' the 
FATS technique (face and thigh 
squeeze). If you take a group of your 
students and have them practice on a 
mannequin without using the FATS 
technique, they won't be able to 
deliver a tidal volume of 800. Also, if 
they don't use a mask that is easy to 
seal, they'll have a hard time. The 
problem that I have with mouth-to- 
mask devices right now is that many 
of the devices have no mechanism for 
increasing the oxygen concentration 
and have no extension tubes. ^" Many 
of them have no filter, relying exclu- 
sively on the valve to protect the res- 
cuer. I was impressed with the paper 

that you did on techniques of emer- 
gency ventilation thai compared the 
Hope Automatic Resuscitation Ven- 
tilator (HARV) to bag-valve-mask 
ventilation in terms of how much 
tidal volume went to the lungs versus 
the stomach.'" The transport ven- 
tilators that were used produced the 
largest tidal volume to the lungs with 
the least amount of gastric insuffia- 
tion. Your test model went beyond 
that used by Melker and Banner by 
including a Laerdal mannequin and 
lung analog in series." This model 
allowed the lung compliance and 
resistance to be varied as well as the 
gastric opening pressure. This type of 
model provides opportunities for 
research that more respiratory ther- 
apists should pursue to find the best 
emergency ventilation techniques. 
Your study was the best designed so 
far, and I congratulate you on work 
well done. Although your study 
showed that mouth-to-mask was 
superior to bag-valve-mask ventila- 
tion in delivering larger tidal vol- 
umes, it also demonstrated that the 
highest airway pressure and inspir- 
atory flow were seen with mouth-to- 
mask ventilation. Consequently, the 
most gastric insufflation occuned in 
your study with mouth-to-mouth and 
mouth-to-mask techniques. Gastric 
insufflation was less with bag-valve- 
mask ventilation and lower still with 
portable ventilators. Isn't that true? 

1. Stewart RD. Paris PM, Winter PM. 
Pelton GH. Cannon GM. Field endo- 
tracheal intubation by paramedical 
personnel: success rates and compli- 
cations. Chest 1984:85:341-345. 

2. Guss DA, Posluszny M. Paramedic 
orotracheal intubation: a feasibility 
study. Am J Emerg Med I984;2: 

3. Pepe, PE. Copass MK, Joyce TH. 
Prehospital endotracheal intubation: 
rationale for training emergency 
medical personnel. Ann Emerg Med 

4. Jacobs LM. Berrizbeitia LD. Bennett 
B, Madigan C. Endotracheal intuba- 

tion m the prehospital phase of 
emergency medical care. JAMA 

5. DcLeo BC. Endotracheal intuhalion 
by rescue squad personnel. Hcarl 
Lung 1977;6:851-854. 

6. Goldenberg IF, Campion BC, Sie- 
bold CM, McBride JW. Long LA. 
Esophageal gastric tube airway vs 
endotracheal tube in prehospital car- 
diopulmonary anest. Chest 1986; 

7. Cummins RO. Austin D. Graves JR. 
Litwin PE, Pierce J. Ventilation 
skills of emergency medical tech- 
nicians: a teaching challenge for 
emergency medicine. Ann Emerg 
Med 1986:15:1187-1192. 

8. Hess D. Ness C, Oppel A. Rhoads 
K. Evaluation of mouth-to-mask 
ventilation devices. Respir Care 
1989:,U: 191-195. 

9. ECRI. Evaluation: exhaled-air pul- 
monary resuscitators (EAPRs) and 
disposable manual pulmonary resus- 
citators (DMPRs). Health Devices 

10. Johannigman J A, Branson RD, 
Davis K, Hurst JM. Techniques of 
emergency ventilation: a model to 
evaluate tidal volume, airway pres- 
sure, and gastric insufflation. J 
Trauma 1991:31:93-98. 

1 1. Melker RJ. Banner MJ. Ventilation 
during CPR: two-rescuer standards 
reappraised. Ann Emerg Med 1985; 

Branson: I'll try to sum this up. I 
can tell you that in the field the intu- 
bation success is very good. The 
problem with that is that you're 
looking at ACLS squads who can 
intubate. There are two types of 
squads, those with paramedics and 
those with only EMTs. The ones 
who have EMTs at this point, are 
either not doing anything or they're 
using terrible things, like esophageal 
obturator airways (EOAs) and pha- 
ryngeotracheal lumen airways (FTL) 
and whatever else is available. So, a 
significant number of people are 
going to be ventilated with a tech- 
nique other than a secured airway — 
if not the entire way to the hospital. 




at least until the paramedic shows up 
at the scene. Right now it 1 were the 
person who was to be ventilated, I 
would want it to he either by mouth- 
to-mask or by an automatic transport 
\entilator — something very simple. 
We use the Impact 706. It has two 
controls — one for rate and one for 
volume. The paramedics can use that 
\ery easily and have two hands to 
hold the mask on the face. If Dr Hurst 
could comment here — he just came 
back from the American Heart Asso- 
ciation conference at which they dis- 
cussed some of these things, and I 
think these things are going to be 
taught to ACLS providers. 
Hurst: The Heart Association work 
group met in Dallas in mid- 
September 1991 prior to the stan- 
dards-revision meeting in Dallas in 
February 1992. The particular sub- 
committee that I was assigned to was 
the ventilation subcommittee, and a 
\ ariety of issues were addressed, one 
of which was extending the inspir- 
atory time to 2 seconds, based on 
Banner and Melker's data' and based 
on the studies that we had done.- 
Likevvise, it was the conclusion of the 
ventilation subcommittee that the 
bag-\alve-mask devices are difficult 
to use and that their use will be de- 
emphasized for one-rescuer efforts. 
The bag-valve-mask devices will be 
de-emphasized for two-rescuer ef- 
forts, too, but their use is being left in 
the training module for the two- 
rescuer effort. There is a move afoot 
to promote the teaching of intubation 
to that intermediate group of Basic 
Life Support (BLS) squads around 
the country. Instead of teaching the 
use of things like EOAs, esophageal 
gastric tube airways (EGTAs), laryn- 
geal mask airways, things of that 
nature — which have been shown in 
many cases to be ineffective and in 
some cases, harmful — to spend that 
time teaching the BLS squads to intu- 
bate. I think that that's going to be a 
major step forward, and a change that 
we're going to .see. I think, likewise. 

that the conclusion of the committee 
is that they are gomg to include a 
training module on transport ventila- 
tion in the new ssllabus. One other 
thing that 1 might add to your data. 
Brenner from Cedars Sinaii in Los 
.Angeles presented his unpublished 
data, in which he polled bystanders, 
health care professionals (nurses and 
physicians), asking them whether 
they WDuld do bystander CPR on an 
unknown adult or on an unknown 
child. Interestingly enough, if you 
look at that one slide you showed 
under the heading "I didn't have 
equipment" and if you add that up. it 
is about 83% if I remember. Bren- 
ner's data also said that physicians 
807^ of the time would not begin 
mouth-to-mouth on an unknown 
adult. Interestingly enough, the poll 
of a group of nurses showed them to 
be more likely to begin mouth-to- 
mouth on an unknown adult. .A poll 
of that same group revealed that onl\ 
509c of them would begin mouth-to- 
mouth on a child. So, I guess, per- 
haps that's telling us something. 

1. Melker RJ. Banner MJ. Ventilation 
during CPR: two-rescuer standards 
reappraised. Ann Emerg Med 1985; 

2. Johannigman J.A, Branson RD, Davis 
K, Hurst JM. Techniques of emer- 
gency ventilation: a model to evaluate 
tidal volume, airway pressure, and 
gastric insufflation. J Trauma 1991; 

Rodriguez: One of the decisions that 
hospitals are facing now is whether to 
have a valve-mask or valve-bag sys- 
tem generally available to their 
employees to ventilate unknown 
adults. What is your recommenda- 

Barnes: 1 would like to think that res- 
pirators therapists are skilled enough 
in the use of a bag-valve de\ice that 
they could effectively ventilate with 
or without a tube in place, in the 
same way that John (Thompson) has 

been able to teach his people to use 
the Mapelson F bag-valve device. In 
adult and pediatric care, therapists 
should be skilled enough to use a 
bag-\alve-mask device. They may 
not deliver 800 mL. but they should 
be at least able to deli\er 600 mL. It 
is unrealistic to think that even crit- 
ical care nurses would be able to use 
a bag-valve-mask device and deliver 
anything much higher than 500 mL. 
In a situation like that, mouth-to- 
mask devices ma\ be the best way 
to ventilate in the time it takes for an 
anesthesiologist or respiratory ther- 
apist to arrive at the resuscitation 
scene. Critical care nurses, floor 
nurses, and other health care pro- 
fessionals should be taught to use 
mouih-to-mask devices, including 
how to seal the mask and hsper- 
e\tend the head. They need to be 
educated regarding the importance 
of providing slow inspiratory flow- 
rates by deli\ering the tidal volume 
over inspiratory time of 1.5 to 2 sec- 
onds. The aspect that needs the most 
research is looking at how much air 
goes to the lungs and how much to 
the stomach in a nonintubated 
patient. This is an area ripe for more 
research and the model that Rich 
Branson developed — controlling vari- 
ables such as lung compliance and 
resistance, gastric opening pressure, 
and face-mask leaks — is the wa\ to 
go. Melker and Banner took the first 
step,' but the Cincinnati group has 
gone funher in developing a test 

1. Melker RJ. Banner MJ. \ entikition 
during CPR: two-rescuer standards 
reappraised. .Ann Emerg Med 1985; 

2. Johannigman JA. Branson RD. Davis 
K, Hurst JM. Techniques of emer- 
gency ventilation: a model to evalu- 
ate tidal \olume. airway pressure, 
and gastric insufflation. J Trauma 

Weaver: One obser\alion: We're a 
Level-I trauma center and com- 




nionly receive patients with closed- 
head trauma and concomitant lung 
contusions. These patients are intu- 
bated either in the field or in the 
emergency department. We've 
obser\ed blood gas alterations that 
imply inet't'ecti\e ventilation by bag- 
valve-mask in intubated patients. So. 
we make a serious attempt to place 
these patients on an appropriate ven- 
tilator early. Even though the ther- 
apist is "bagging" in a hyper- 
ventilation mode, we're still dealing 
with acidemia and hypercarbia 
because of the lung contusion and. 
usually, severe gas exchange abnor- 
malities. What we try to do is to con- 
nect them to our transport ventilator, 
which far exceeds the capability of 
human hands with bag-valve-mask 
technique. I bring it up Just to see if 
anjone here has had similar observa- 
tions or if you've considered that. 
Barnes: That's a very important 
comment to make because of the 
argument for synchronous ventila- 
tion — ventilation done at the same 
time that chest compressions are 
done — versus asynchronous ventila- 
tion — with ventilation done between 
chest compressions. The ad\ antage of 
synchronous ventilation is that the 
chest compression seals off the 
esophagus: so. air is less likely to go 
to the stomach during the time that 
gas is trying to work its way into the 
lung. You can also achieve slower 
inspiratory times, if you're not wor- 
rying about trying to deliver that ven- 
tilation between chest compressions. 
Quite a bit of work has already been 
done, and you might in the future see 
a case being made for synchronous 
ventilation, rather than asynchronous 
ventilation during CPR.''^ I agree 
with you that the need to take some- 
one off a ventilator when chest com- 
pressions are going on is probably a 
misunderstanding. It probably is not 
necessary if the peak inspiratory pres- 
sure is adjusted appropriately. 

1. Melker RJ. Asynchronous and other 
alternative methods of ventilation 

during CPR. .Ann Emerg Med 

2. Harris LC. Kirmli B. Safar P. Ventila- 
tion — cardiac compression rates and 
ratios in cardiopulmonary resuscita- 
tion. Anesthesiology 1967:28:806- 

3. Chandra N. RudikotT M, Weisfeldt 
ML. Simultaneous chest compressions 
and ventilation at high airway pressure 
during cardiopulmonary resuscitation. 
Lancet 1980;1:175-178. 

Kacmarek: How safe are the mouth- 
to-mask devices? In one slide that 
you showed, only 667r or so had fil- 
ters. We've been reluctant to distrib- 
ute any of those devices in our insti- 
tution, for fear of creating the false 
impression of safety, when in fact 1 
don't know of any data that have 
really demonstrated that they are safe 
to use and that they do prevent the 
mo\ ement of any substance from the 
patient to the caregiver. We've con- 
tinued to provide bag-valve-mask 
devices readily throughout the institu- 
tion (in preference to mouth-to-mask) 
because of that particular issue. 
Barnes: Disposable bags are now 
$20 apiece, sometimes $17 apiece; 
so. the expense argument isn't going 
to keep you from using bag-valve- 
masks. It all depends on how much 
confidence you have in the recent 
study done by ECRI in Philadelphia.' 
during which they looked at 1 7 mouth- 
to-mask devices. They poured a dye 
solution into the proximal side of the 
mask, and none of it came through the 
valve — retrograde through the valve. 
Dean (Hess). I know that you've 
looked at that. 

1. ECRI. E\aluation; exhaled-air pul- 
monary resuscitators (EAPRs) and dis- 
posable manual pulmonary resus- 
citators (DMPRs). Health Devices 

Hess: We looked at that and pub- 
lished it in abstract form a couple of 
years ago.' 1 think Bob's (Kacmarek) 
concern is at least partially legit- 

imate. When we looked at back leak 
through the valves on these devices, 
indeed some of them do leak, using 
just oxygen as a tracer. 1 think that 
the devices do provide a barrier, and 
that's about all. They are not 100% 
foolproof, and 1 think we do need to 
be concerned that people not think 
that they are 100% absolutely fool- 
proof and that you cannot get 
infected if you use one of these 
devices. Something else about bag- 
valve-mask devices and some of the 
work we did.- I think there's the 
issue of efficacy, and I believe that 
if you take respiratory care practi- 
tioners, nurses, physicians. EMTs, 
paramedics, and others and spend 
enough time working with them, 
you can get them to deliver rea- 
sonably good volumes with the bag- 
valve-mask device. The ony prob- 
lem is that many times that skill is 
not retained for very long, and when 
individuals need to use that skill in 
an arrest situation, they don't per- 
form very well, as in our study that 
showed that volumes of only 300 
mL on the average were delivered. - 
We brought people to the lab. Some 
of them were students, second-year 
students in the clinical year of their 
training, some were actually practi- 
tioners, and some of them were even 
supervisors in a respiratory care 
department. We asked them to ven- 
tilate the mannequin as they would 
ventilate a patient if they showed up 
in an arrest. We did not give them a 
lot of time to practice and to figure 
out how to deliver good volumes 
because in an arrest situation that's 
the reality. You don't have 15 or 20 
minutes to practice before you have 
to begin performing. Interestingly, 
in our study there was no statistical 
difference between the volume that 
the experienced people (the RRTs) 
were able to deliver versus the sec- 
ond-year respiratory therapy stu- 
dents. One of the other things we 
looked at was the volume delivered 
if one person used the bag versus if 




two persons used the bag. With the 
two-person technique, one person 
held the mask and opened the airway 
with both hands. A second person 
squeezed the bag with both hands. 
The volumes were much better, sig- 
nificantly better, with the two-person 
technique, and. in fact, the voluines 
with the two-person technique were 
similar and, as I recall, were not sta- 
tistically different from the volumes 
with the niDUlh-to-mask technique. 
So. I think if one is going to use the 
bag-\alve-mask technique, it"s impor- 
tant to teach a l\\ o-person technique. I 
think one of the things that our data 
demonstrate is that it's difficult for 
people to look at chest movement and 
know how much gas goes into the 
patient or to be able to tell by some 
type of an educated guess what kind 
of a tidal volume they're delivering. 

One of the ways that we can over- 
come that is by measuring the vol- 

1. Hess D. Kukula C. Evaluation of 
backleak through mouth-to-mask ven- 
tilation devices (abstract). Respir Care 

2. Hess D. Baran C. Ventilatory volumes 
using mouth-to-mouth, mouth-to- 
mask, and bag-valve-mask techniques. 
Am J Emerg Med l985:.3:292-296. 

Barnes: We did show a slide of a 
one-hand and two-hand comparison 
from your study, and it was compar- 
able to mouth-to-mask. The mouth- 
to-mask device designed in 19.^4 
wasn't a bad design because it 
extended the distance of the rescuer's 
face from the patient, allowed two 
hands to hold the mask, and got away 
from this filter, nonrebreathina-valve 

leak problem.' The tube-valve-mask 
device from Canada that delivers 
90*^ oxygen by using a 1.300 niL 
oxygen reservoir does basically the 
same thing.- However, it's a very 
cumbersome design: if therapists 
think about it long enough, they 
should be able to come up with a 
design that has an adequate oxygen 
reservoir, delivers a high oxvgen 
concentration, and separates the res- 
cuer from the v ictim adequately. 

Elam JO, Brown ES. Elder JD Jr. 
Artificial respiration by mouth-to- 
mask method. N Engl J Med 1954: 

GilTen PR. Hope CE. Preliminarv 
evaluation of a prototype tube-valve- 
mask ventilator for emergency artifi- 
cial ventilation. Ann Emerg Med 



Airway Management Options 

H David Reines MD 


The method chosen to intubate the trachea for 
the purpose of ventilation and oxygenation depends 
on (1 ) the situation, emergency or elective. (2) the 
a\ailability of equipment. (3) the skill and expe- 
rience of the practitioner. (4) the indications for the 
procedure, and (5) the long-term goal of the intuba- 

The four major approaches to controlling the air- 
way are ( 1 ) naso- or orotracheal intubation with an 
endotracheal tube (ETT). (2) direct surgical access 
via cricothyroidotomy or tracheotomy. (3) per- 
cutaneous access via needle cricothyroidotomy or 
percutaneous tracheotomy, and (4) insertion of an 
esophageal or pharyngeal airway. 

This paper is limited to a discussion of non- 
elective intubation for airway control in patients 
following trauma or in the ICU. I concentrate on 
the indications, methods, and complications of each 
of the major techniques of airway intubation. Gen- 
eral indications for the intubation of the airway are 
listed in Table 1 . 

Intubation in Trauma 

Patients who have sustained major trauma have 
unique airway needs because of the potential for 
airway obstruction in the face of possible cervical 

Dr Reines is an Associate Professor of Surgery/Anesthe- 
siology. the Medical College of Virginia. Virginia Common- 
wealth University. Richmond. Virginia. 

A version of this paper was presented by Dr Reines on October 
4. 1991. during the Respiratory Cari; Journal Conference on 
Emergency Respiratory Care held in Cancun. Mexico. 

Reprints: H Da\ id Reines MD, Medical College of Virginia, 
Virginia Commonwealth University. PO Box 475. MCV Sta- 
tion, Richmond VA 23298-0475. 

spinal-cord injury. The priorities in the trauma vic- 
tim are no different from those in any emer- 
gency — airway, breathing, and circulation. How- 
ever, unique considerations may include (!) the 
need to establish the airway in the presence of 
facial and/or laryngeal injury and (2) the need to 
ventilate for severe chest or head injury, while 
avoiding neurologic injury from instability of the 
cervical spine. 

The procedure of choice for establishing an air- 
way in the traumatized patient is blind nasal intu- 

Table 1. Reasons for Establishing Airway Control 

To maintain airway patency 

For deliver^' of general anesthesia 

For hyperventilation of head-injury patients 

For ventilation of paralyzed patients for prolonged 

For ventilation of drug overdose patients 

To prevent aspiration secondary to altered level of 
consciousness or to glottic or cord dysfunction 

To ventilate when airway obstruction is present or 


To treat respiratory failure 

Uncompensated chronic obstructed pulmonaiy 

Severe asthma 
Severe chest trauma 

To clear secretions 

To facilitate delivery of high oxygen concentrations and/or 
positive end-expirator> pressure (PEEP) 




hation because it does not require moving the cer- 
vical spine or medication (ie. sedation or paralysis) 
for success. If nasal intubation is not possible or 
contraindicated secondary to midface trauma, the 
clinician is left with two alternatives; oral intuba- 
tion with in-line traction or surgical cricolhyroid- 

Nasotracheal Intubation 

Nasotracheal intubation (NTT) should be per- 
formed as an emergency procedure in any patient 
breathing spontaneously who requires airway pro- 
tection or ventilation. The patient should be mask- 
bag preoxygenated. If time allows, a nasal airway 
and local anesthetic are useful; however, this fre- 
quently is not possible, and a 7- or 8-mm ETT 
should be placed rapidly through the nares and into 
the trachea. This procedure is contraindicated if 
midface fractures or nasal bleeding is present or if 
the patient is not breathing.' If NTI is not immedi- 
ately successful, other airway management should 
be used. NTI can damage the posterior turbinate of 
the nose and cause severe bleeding, and should 
only be performed by experienced personnel. 

It is desirable to obtain a lateral film of the cer- 
vical spine to the level of C7 (ie, the seventh cer- 
\ical vertebra) prior to intubation to establish the 
presence or absence of spinal injury. Although this 
is a good screen, a cross-table lateral spine film is 
only 74-829^ sensitive.- When the condition of the 
neck is unknown and injury is suspected, mo\e- 
ment of the neck should be axoided. Crosby and 
Lui" quote an Egyptian physician who described 
cervical-spine injury more than 4,500 years ago; 

One having a dislocation in a vertebra of his neck 
while he is unconscious, his two legs and his two 
arms and his urine dribble, is an ailnionl nol to be 

movement at C6-7 level.^'^ Despite this, several 
series report no complications when intubation is 
performed with two people, one maintaining "in- 
line traction" and one intubating without extending 
the neck." ' Of 8,712 trauma victims admitted to the 
Maryland Institute Emergency Medical Services 
System (MIEMSS) over a 5-year period, 4,267 
(49%) required intubation.^ A subset of 1.158 
patients required intubation immediately following 
admission without the benefit of cervical-spine 
radiography. Of these, 81 (7%) were subsequently 
found to have spinal-cord injury with no evidence 
of deterioration following oral intubation. The pro- 
cedure of choice at MIEMSS is translarsngea! intu- 
bation using paralysis, thiopental, lidocame. cricoid 
pressure, and in-line traction followed by oral intu- 
bation. Only 29 patients (0.19c) required crico- 
thyroidotomy in this series. Therefore, it appears 
that orotracheal intubation (OTI) is safe in patients 
with neurologic injury."^ For these reasons, the 
American College of Surgeons Advanced Trauma 
Life Support (ATLS) course and others ha\e 
approved in-line traction and oral intubation when 
NTI is not indicated (Pis. 1 ).' '' 

Unconscious, with blunt trama 

Suspect cervical spine injury 

Airway urgency 

Immediate need 


Oxygenate ^/entilate 



with 1 





acheal < - - ■* Po 



ization Sb\ 

^ maxilt 

*■ injury, p 

1 ability to 



No immediate need 


Obtain C-spine 





Surgical airway 

Proceed according to clinical judgment 

Fig. 1. Algorithm for establishing airway control. 
(Reprinted, with permission, from Reference 1.) 

Orotracheal Intubation 


Although immobilization in suspected cervical 
injury is desirable, it may be ditficult to achieve. A 
soft collar allows 96'7f neck tlexion and lYA exten- 
sion, whereas the .stiffer Philadelphia collar still 
allows up to 35% of normal extension.' Several 
studies of cervical-spine motion have been per- 
formed on cadavers demonstrating up to a 7.5-mm 

When facial trauma precludes intubation or intu- 
bation is difficult, cricothyroidotomy may be 
employed.'" (Tracheotomy has little place in the 
management of acute iiauma because it takes 
longer to perform and has more complications as 
an emergenc)' procedure than does cricothy- 




A percutaneous needle catheterization leclmique 
has been utilized in inuniia patients with occasional 
success. Transtracheal catheter insertion with jet 
ventilation was first described in 1936 by Jacoby et 
al," and has been utilized in numerous animal and 
human subjects over the past 25 years. The anat- 
omy in\olved in percutaneous needle crico- 
thyroidotomy is shov\n in Figure 2. The cricoid- 
thyroid membrane is located by palpating up the 
neck from the sternal angle until the cricoid cartil- 
age is located. The skin is rapidly prepared with 
antiseptic and at least a 14-gauge needle or catheter 
is placed into the trachea at a 75-90" angle through 
the membrane. When air is aspirated easily, the 
catheter or needle is attached via a 3-mm pediatric 
endotracheal adapter to a high-pressure system 
such as a jet ventilator. Its use in trauma has been 
demonstrated by Jordan et al.'- Percutaneous crico- 
thyroidotomy has its greatest use in partial airway 
obstruction in head and neck trauma." Others'"* 
have recommended that needle cricothyroidotomy 
with jet ventilation not be used in complete airway 
obstruction because of the possibility of air trap- 
ping. An alternative method for transtracheal ven- 
tilation that utilizes a percutaneously placed 8.5-Fr 
Swan-Ganz introducer has ventilated totally 
obstructed dogs with a bag and mask with excellent 
blood-gas results.'"" 






Fig. 2. Anatomy relevant to performance of cricotliy- 
roldotomy. (Reprinted, with permission, from Reference 

The surgical cricothyroidotomy is preferred to 
tracheotomy because the cricoid membrane is 
superficial in the neck, has no overlying thyroid 
gland or major vessel, and does not require the 
neck to be extended to gain access.'* The neck is 

quickly prepared with an antiseptic solution and 
stabilized, with the left hand holding the lateral 
aspects of the cricoid cartilage. With a #11 blade 
held perpendicular to the skin, a 1- to 1.5-cm stab 
wound is made and either the back of the .scalpel 
handle or a hemostat is u.sed to enlarge the hole. A 
standard 6-mm cuffed tracheostomy tube or a 6- to 
7.5-mm HTT is placed into the incision and ventila- 
tion begun."' 

Cricothyroidotomy can be performed by any 
qualified person, including helicopter personnel, 
field paramedics, and emergency room personnel. I 
have found it to be quick, relatively safe, and easy 
to learn. 

'Esophageal' Airways 

Several alternatives to endotracheal intubation 
(ETI) have been attempted with varying results. 
The assumptions that ( 1 ) nonphysicians could not 
easily perform ETI and (2) tubes naturally go into 
the esophagus, led to the development of the esoph- 
ageal obturator airway (EOA) by Don Michael and 
Gordon.'" Based on preliminary data, the EOA was 
approved for use in cardiopulmonary resuscitation 
(CPR) and trauma."* In an uncontrolled clinical 
study reported in 1976, 18 patients were intubated 
with an EOA and then with an ETT,''' with no com- 
plications. Ventilation was performed by an expe- 
rienced respiratory therapist, and arterial blood 
gases were obtained only after \entilation was 
judged to be adequate. The survival rate was not 
reported. The EOA also was tested in the operating 
room under controlled conditions.-" The delivered 
volume was less than with the ETT, and the face- 
mask seal was difficult to obtain. Thirty percent of 
the patients had inadvertent tracheal intubation. 
Don Michael and Gordon-' in a retrospective study 
have reported EOA intubation of 29,000 subjects. 
Based on minimal new data, a study by Meislin 
concluded that "EOA ventilation is essentially as 
effective as endotracheal ventilation" in the emer- 
gency room and when the patient is not moved. -- 

However, complications with the EOA soon 
began to be reported, especially aspirations, endo- 
tracheal intubations, and esophageal ruptures sec- 
ondary to the removal of the device with the esoph- 
ageal balloon infiated.-' As more complications 
related to the EOA were reported, the esophageal 
gastric tube airway (EGTA) was developed to 




decrease gastric aspiration b\ allowing placement 
of the nasogastric tube through the gastric lumen of 
the tube (Fig. 3). 



ADAPTOR. [ 4^''''^ 




— 30ML 

Fig. 3. Components of an esophageal gastric tube air- 
way. (Reprinted, with permission, from Reference 1.) 

The use of esophageal airways came into ques- 
tion in 1982 when Bass et al reported 100 of 
attempted EOA intubation uith an 88% success 
rate (729f first try)r^ however, a tight seal was dif- 
ficult to obtain in 15 patients. An evaluation of 158 
cases of prehospital cardiac arrest yielded an 82% 
EOA intubation success rate but noted that all 
patients were hvpercarbic with a mean Paco^ of 

The advantages of the EOA/EGTA were 
reported to be ( 1 ) emergency medical service per- 
sonnel could be easily trained in its use, (2) ease of 
in.sertion. and (3) ease of use. None of these has 
proven to be true. Although less than 2 hours are 
required for training, the poor mask fit and like- 
lihood of esophageal intubation make it difficult to 
use in an ambulance. The recommendation from 
the Committee on Trauma from the American Col- 
lege of Surgeons is not to use EGTA and EOA 
because they are considered to be "ineffective."' 
Furthermore, if placed in the field, the EGTA 
should be remo\ed onl\ under liirect \ ision when 
the ETT can be placed in the trachea. The EGTA 
should not be removed until tracheal intubation is 
complete to avoid the possibility of aspiration. 

A new addition to the prehospital A TLS arma- 
mentarium is the pharyngeal-tracheal lumen airway 
(PTLA).-' This device (Fig. 4) is similar to the 
EGTA: however, its use seems to be associated 
with fewer complications and a higher success rate 
than its predecessors."* 

Tracheal Intubation in the Field 

There is liiiic question that ETI is the preferred 
method of emergency airway control. For numer- 
ous reasons, ETT use has not been widespread in 
the field until recently." Among these reasons are 
reluctance by physicians to train nonphysicians and 
concerns over esophageal intubation, prolonged 
intubation time, and pharyngeal damage. DeLeo-** 
has reported a 919^ success rate with less than 2 
hours training, although Guss and Posluszny 
reported that 6-10 hours of training are needed to 
achieve an Sb'/c success rate.-*^ Patients suffering 
severe falls, traumatic arrest, and severe head 
injury all benefit from field intubation, compared to 
patients without artificial airways.-" 

As more field personnel have become proficient 
in ETI and because the ETT need not be replaced, 
the EOA and EGTA ha\'e fallen out of fa\c>r and 
are rarely used by paramedics. As Pttns concluded 
in his review,'" "All who advocate the use of EO.A/ 
EGTA agreed that the ET tube was the optimal 
way of securing or protecting the airway." Airway 
control in the emergenc>' department means tra- 
cheal intubation, not esophageal airv\ay manage- 

Fig, 4. The pharyngeal-tracheal lumen airway as it is 
placed in a patient. (Reprinted, with permission, from 
Reference 1.) 


RFSPIRATORY CARF • .lULY "92 Vol 37 No 7 


mcnl, and 1 belie\c that in the I'leld it should be tlie 

Airway Control in the Intensive Care L'nit 


Respiratory failure and postoperative \entilation 
are two of the most common causes of ICU admis- 
sion. Three controversies that continue to dominate 
airway management are ( 1 ) naso- \ersus oro- 
tracheal intubation (NTI vs OTI), (2) the timing 
and necessity for tracheotomy, and (3) who should 
perform emergency intubation of adults in the hos- 

When available, a skilled anesthesiologist or 
nurse anesthetist is the person of choice. "Rigorous 
credentialing of personnel who perform tracheal 
intubation should reduce the incidence of complica- 
tion."'' If a trained anesthesiologist is not available. 
another physician trained to intubate should be 
available. In smaller hospitals (< 200 beds), the res- 
piratory therapist is frequently the most qualified to 
perform emergency intubation, as determined in a 
poll performed b\ the National Association of 
Medical Directors of Respiratory Care (personal 
communication. Barr\ Shapiro. Northwestern Uni- 
versity Medical Center. Chicago IL. 1991 ). 

Again, the route of intubation chosen depends 
on the situation and the experience of the operator. 
Blind NTI requires a breathing patient; therefore, in 
a cardiac arrest, OTI is necessan,. Intubation for 
respiratory failure ma> require paralysis if rapid 
tracheal access cannot be obtained in a gasping, 
hypoxic patient. Establishing a surgical airvsay is 
almost ne\er an emergency procedure in hospital- 
ized patients. 

Complications of Prolonged Intubation 

In the past, the major complication of prolonged 
intubation has been tracheal stenosis secondary to 
pressure necrosis from high-pressure cuffs and stiff 
tubing. The introduction of soft, disposable, poly- 
vinyl tubes with floppy, low-pressure, high-volume 
cuffs has had an important impact on this problem 
(Fig. 5).'- I believe that clinically significant tra- 
cheal stenosis is now rare among intubated adults. 

One way to avoid major tracheal injury is to 
monitor cuff pressure and use a minimal leak tech- 
nique (MLT) to maintain airways.-^-' •^"' Manometry 
u ith maintenance of cuff pressure at > 25 cm HiO 
ma> protect the tracheal mucosa from ischemic 
necrosis; however, in patients uith noncompliant 
lungs requiring high peak inspirator) pressures, a 
25-cm limit may not be possible.'" The higher cuff 
pressure seen when peak inspiratory pressure is 
greater than 25 cm H^O may be a reflection of the 
effect of airway pressure on the cuff instead of 
pressure exerted against the trachea. MLT is more 
practical as a technique and is applicable in a 
majority of patients; however, no technique is a 
guarantee against tracheal malacia and the develop- 
ment of tracheoesophageal fistula. Care and vig- 
ilance are necessary to prevent these problems. 

Prolonged nasal intubation has been associated 
with an increased incidence (2-57f) of paranasal 
sinusitis, which is difficult to discover and can lead 
to fever of unknown origin with important sequelae 
(including brain abscess) when not drained prop- 
erly.' Sinusitis can arise in any patient naso- 
tracheally intubated for longer than a few days, and 
should be suspected in a patient who has been intu- 
bated nasotracheally for a week."* We tr>' to limit 
our nasotracheal intubations to > 5 days. 

Fig. 5. Results of simultaneously inflating each of 8 tube 
cuffs to 20 torr. Tfie tubes are arranged alphabetically 
from left to right as follows: Argyle, Harris-Lake, Lanz, 
National Catheter, Portex, Shiley, and Surgitek. (Re- 
printed, with permission, from Reference 32.) 

RESPIRATOR^' CARE • JUL^' "92 Vol 37 No 7 



Oral tracheal tubes are somewhat more difficult 
to maintain and position because ol dilTiculty with 
taping to the mouth, and because of the occasional 
need for an oral airway or bite block to prevent the 
patient from biting on the tube. It may be difficult 
to prevent some patients from dislodging the tube 
with their tongues. Adapters and tube holders are 
available to stabilize and maintain tube position. 
OTI does allow a somewhat larger airway and is 
not associated with sinusitis. Orotracheal tubes 
may be easier to suction because of the absence of 
an acute angle posteriorly. 

A life-threatening problem with intubation is 
unplanned (accidental) extubation. Between 8.5% 
and W/c of all intubated critically ill patients expe- 
rience accidental extubation."' The use of restraints 
does not seem to alleviate this danger; rather, the 
appropriate use of sedation, careful attention to tap- 
ing, and avoiding torque on the tube are the most 
important determinants of tube maintenance. 

Both naso- and orotracheal tubes ha\e the dis- 
advantage of traversing the vocal cords and causing 
pressure throughout the pharynx.""' Furthemiore, 
significant motion in the trachea is possible when 
the patient fiexes or extends his head with the tube 
secured to the nose and mouth. For these reasons, 
more than for the prevention oi tracheal stenosis, 
tracheotomy should be considered earl\ \n the 
course of patients requiring prolonged intubation. 
The recommendations of the ACCP Consensus 
panel aie"' 

• For anticipated need of the artificial airway 
up to 10 days, the translaryngeal route is pre- 

• For anticipated need of the artificial airway 
for greater than 21 days, tracheostomy is pre- 

• When the time anticipated for maintenance of 
an artificial airway is not clear, daily assess- 
ment is required to determine w hether con\er- 
sion to tracheostomy is indicated. 

• The decision to convert to tracheostomy 
should be made as early as possible. 

Although 3 days of intubation probabls are not 
extremely harmful, patients projected to need pro- 
longed intubation (> 3 weeks) should be considered 
for early tracheotomy when they are stable. 

The .'Vdvantafjes and Disadvantases 
of Tracheotomy 

Comparing ETI with tracheotomy is difficult 
(Table 2)."" In one prospective study of 150 intu- 
bated patients, 97 had only endotracheal tubes and 
53 underwent tracheotomy (46/53 had ETTs before 
tracheotomy): 5139c of all patients died and 62^r 
had at least one problem related to endotracheal 
intubation. Self-extubation. right main-stem intuba- 
tion, tracheal stenosis, excess cuff pressure, and 
subcutaneous emphysema were all seen. The inci- 
dence of tracheal stenosis (> lO'^'r on lateral neck 
film) was 19% in the group only intubated and 

Table 2. Translap, ngeal Intubation versus Tracheotomy* 


Variable Tracheotomy 


Surgical procedure 




Permanent airway? 



Reintubation requires 

skilled personnel? 

First 24-38 hours? 



After 48 hours? 



Sedation, relaxants? 

First 24-48 hours? 



After 48 hours? 



Accidental extubation 



Upper-airway trauma 



Laryngeal damage? 






(with nasal 

Oral hygiene 


Difficult with 
oral tube 

Tube size 

Wider, shorter 

Narrower, longer 

Flow resistance 





More difficult 

Massive hemorrhage? 

Yes. rare 


Main-stem intubation 



Stomal complications? 



Airway infections 

Perhaps more 

Perhaps less 

Patient comfort 

Perhaps greater 

Perhaps less 


from Reference 4 1 . 


♦Adapted, with permission. 




657c of tlic 17 paiK'iits in (lie trachoDslomy group 
studied, all of u hoiii had been transtracheally intu- 
bated as well. At autopsy, 95% of patients with 
ETTs and 9\7c of those with tracheostomies had 
laryngotracheal injury."' Other studies have com- 
pared tracheotomy to endotracheal tube. Whited'*' 
prospectively examined ? groups of patients. 
Group I was intubated 15 days. Group II 6-10 days, 
and Group III 1 1 or more days. All patients were 
endoscoped within 24 hours of extubation, and 
again 3-6 months later. Group I all showed mild-to- 
moderate injury to the posterior laryngeal com- 
missure. In Group II. 5 of 74 patients showed sig- 
nificant cord or laryngeal damage. Sequelae includ- 
ing aspiration secondary to glottic incompetence 
occurred in 12 of 30 patients. The advantages of 
tracheostomy include easier access for pulmonary 
toilet, patient comfort, and ability to speak.'*' A 
recent study "'"' demonstrates that early tracheotomy 
(< 8 days) performed electively for trauma de- 
creases morbidity and hospital stay. Previously, tra- 
cheotomy had been considered a morbid procedure 
w ith complication rates of 3?^% and mortality of 2- 
5%.*^ Recently, the complication rates for both ETI 
and tracheotomy ha\e been comparable. In another 
study of 81 patients with elective surgical tra- 
cheotomy,'*'^ no deaths, no loss of airway for longer 
than 20 seconds, no obstruction, and no blood loss 
greater than 15 mL were noted, with only minimal 
intraoperative complications. Major complications 
of tracheostomy (necrotizing infection, tracheal 
innominate fistula, and pneumothorax) are rare 
(Table 3).^'' Several percutaneous techniques have 
evolved for rapid tracheotomy. Schachner et al'*'' 
have described a percutaneous technique involving 
tracheotomy and a modified Seldinger technique. A 
multicenter study"*^ of this technique in 61 patients 
yielded a 909^ success rate, with 3 minor complica- 
tions, in an average time of 3-5 minutes. There was 
one death from bronchospasm. 

Tracheotomy Techniques 

The standard surgical tracheotomy is best per- 
formed in the operating room with the patient's 
head extended. Either a vertical or horizontal inci- 
sion is made over the second and third tracheal 
rings. Dissection is carried down through the mid- 
line subcutaneous tissues, the strap muscles are 

Tabic 3. Early and Late Complications ot Tracheotomy* 

Complication Occurrence 



Standard tracheotomy 
Subcutaneous emphysema 
Incisional hemorrhage 



Incisional hemorrhage 

( rare ) 
Laryngeal injury 

Tracheal stenosis 


Tube obstruction 

Swallowing dysfunction 
Stomal infection 

Tracheal & subglottic 

Tracheoesophageal fistula 
Tube obstruction 

Swallowing dysfunction 
Stomal infection 

'Adapted, with permission, from Reference 6. 

retracted laterally and the thyroid gland retracted 
superiorly. Occasionally the thyroid isthmus must 
be divided for exposure. Either a vertical I-shaped 
incision with lateral stay sutures or an interiorly 
based upside-down-U flap is performed and the 
largest tube that easily fits is inserted. For adults an 
8-mm tracheostomy tube should be placed to avoid 
airway compromise. This procedure takes 15-30 
minutes and can be performed under general or 
local anesthesia. The percutaneous tracheotomy 
technique is best performed in the operating room 
for optimal lighting, positioning, and airway con- 
trol; however, it can be performed at the bedside. 
The technique involves partial withdrawal of the 
ETT and a small incision through the skin and sub- 
cutaneous tissue.'*'' A curved needle is inserted and, 
when air is aspirated, a thick guide wire is inserted 
and the needle removed. The tracheostome dilator 
is then inserted over the wire and opened to allow 
passage of the tracheostomy tube into the trachea. 
In patients with exceptionally thick necks, a cut 
endotracheal tube with cuff and pilot balloon intact 
niay be used (Figs. 6A & 6B). 




Fig. 6A. Demonstration of technique for 
percutaneous tracheotomy. (Reprinted. 
with permission, from Reference 1.) 

Fig. 6B. Instrument l<it used for per- 
cutaneous tracheotomy. {Reprinted, 
with permission, from Reference 1.) 




Overall, the data are equixocal on the need tor 
early tracheotomy. It has been our practice to per- 
t'orni tracheotomy within 7-14 days on any patient 
w ho cannot be v\eaned or has been extubaled twice 
and had to be reintubated. Also, patients who need 
long-tenn ventilation or have experienced any aspi- 
ration and required intubation should undergo early 
tracheotonn. Whether a cricothyroidostomy needs 
to be con\ erted to a tracheostomy is a controversial 
subject. Although some data have suggested that 
cricothyroidotomy has a high incidence of cord 
damage and stenotic sequelae.'^" a study by Bran- 
tigan and Grow^' reported their experience with 
655 long-term cricothyroidotomies with no sub- 
glottic stenosis. 

Emergency Airways in Children 

Important anatomical differences in young chil- 
dren and neonates alter their airway management 
from that employed for adults. Small children, 
especially those under the age of 3 years, have the 
narrowest portion of their airway immediately 
below the glottis at the cricoid. Therefore, place- 
ment of an endotracheal tube as large as the cords 
will accommodate is not indicated and may cause 
tracheal stenosis. Furthermore, the use of cuffed 
endotracheal tubes in small children is neither nec- 
essary nor indicated because of the pliant nature of 
the trachea and the propensity for significant tra- 
cheal stenosis leading to lifelong difficulty. Like- 
wise tracheotomy should be avoided when possible 
in neonates because of the long-term sequelae, the 
problems of occlusion from secretions, and the rel- 
ative ease of intubation in very small children.^" 

The majority of pediatric cardiac arrests are 
caused by airway obstruction or pulmonary prob- 
lems and not trauma. Immediate orotracheal intuba- 
tion is the preferred method of airway control. Nee- 
dle cricothyroidotomy is occasionally necessary; 
however, surgical cricothyroidotomy should be 
avoided because of the long-term sequela of tra- 
cheal stenosis. ■"' In one study of 100 consecutively 
intubated children, \09c of those orotracheally intu- 
bated and 1 1 % of those with nasotracheal tubes had 
major complications compared to 26% of children 
with tracheostomy. Laryngotracheal bronchitis 
(croup) was associated with the highest complica- 
tion rate.'''' Tracheostomy for prolonged ventilation 

loses many of the advantages of the surgical airway 
seen in adults; however, in a study of 142 children 
undergoing tracheotomy, there were 2 tracheos- 
tomy-related deaths, 13 persistent fistulas, and 19 
instances of therapy required for granulomas and 
polyps. Stenosis was rare.''^ 

In Summary 

In general, management of the airway in crit- 
ically ill or traumatized patients should follow sev- 
eral guidelines. Airway control and ventilation are 
the first priorities in the management of any crit- 
ically ill patient. If a patient is to be intubated, pre- 
oxygenation and intubation by a skilled practitioner 
are mandatory. In trauma, nasotracheal intubation 
in a breathing patient or oral intubation with in-line 
traction performed by knowledgeable individuals is 
our first choice when possible. When neither of 
these is possible, surgical cricothyroidotomy 
should be utilized. Prolonged nasotracheal intuba- 
tion in the adult ICU patient should be avoided and 
tracheotomy considered at 7-10 days. Tracheotomy 
and cricothyroidotomy should be avoided in chil- 
dren when possible. The use of percutaneous tra- 
cheotomy shows promise for the future. In all 
cases, safe tracheal extubation should be performed 
as early as the underlying disease allows. 


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Wu WH. Lim IT. Simpson ¥.\. Tumdorf H. Pressure 
dynamics of endotracheal and tracheostomy cuffs. Crit 
Care Med 1973;4:197-202. 

Bernard WN. Yost L. Joynes D. et al. Just seal intracuff 
pressure during mechanical ventilation (abstract). Anes- 
thesiology l982:57(Suppl):A145. 

Off D. Braun SR, Tompkins B. Bush G. Efficacy of the 
minimal leak technique of cuff inflation in maintaining 
proper intracuff pressures for patients with cuffed arti- 
ficial airways. Respir Care 1983:28:1 1 15-1 120. 
Badenhorst CH. Changes in tracheal cuff pressure dur- 
ing respiratory support. Crit Care Med I987;15(4):300- 

Deutschman CS. Wilton P. Sinow J. Dibbcll D, Kon- 
stantinides FN. Cerra FB. Paranasal sinusitis associated 
with nasotracheal intubation: a frequently unrecognized 
and treatable source of sepsis. Crit Care Med 1986:14: 

Linden BE. Aguilar EA. Allen JJ. Sinusitis in the naso- 
trachealh intubated patient. .Arch Otolaryngol Head 
Neck Surg 1988:1 14:860-861. 

Stauffer JL, Olson DL, Petty TL. Complications of con- 
sequence of endotracheal intubation and tracheostomy: 
a prospective study of 150 critically ill adult patients. 
Am J Med 1981:70:65-76. 

Heddin M. Ersoz C, Donnelly W . Laryngotracheal dam- 
age after prolonged use of orotracheal tubes in adults. 
JAMA 1969:207:703-708. 

Civetta J.M. Taylor RW. Kirhy RR. eds. Critical care. 
Philadelphia: JB Lippincott, 1988:202. 
Whited RE. A prospective study of laryngotracheal 
sequelae in long term intubation. Laryngoscope 1984: 

Rixiriguez JL. Steinberg SM. Luchetti F.-\. Gibbons KJ. 
Taheri PA. Flint LM. Early tracheostomy for primary 


RHSPIRATORY CARE • JUL^ "92 Vol 37 No 7 


airway management in ihc surgical critical care setting. 
Surger\ 19TO; 108:653-659. 

44. Meade JW. Tracheostomy — its complications and their 
management. N Engl J Med 1961:265:519-523. 

45. Stock MC. Woodward CA. Shapiro BA. Perioperative 
complications of electi\e tracheostomy in critically ill 
patients. Crit Care Med 1986;I4:861-S64. 

46. Heffner JE, Miller KS, Sahn SA. Tracheostomy in the 
intensive care unit. Pan I & 2. Chest 1986;90:430-436. 

47. Schachner A, Ovil J. Sidi J, Avran A. Levy MJ. Rapid 
percutaneous tracheostomy. Chest 1990:98:1266-1270. 

48. hatury RR. Siegel JH. Stahl WM. Simmon Ro Scorpio 
R, Gens DR. Percutaneous tracheostomy after trauma 
and critical illness. J Trauma 1992:32:133-140. 

49. Schachner A. Ovil Y. Sidi J. Roger M. Heilbronn Y. 
Levy MJ. Percutaneous tracheostomy: a new method. 
Crit Care Med 1989:17:1052-1056. 

50. Kennedy T. Epiglottic reconstruction of laryngeal steno- 
sis secondary to cricothyroidotomy. Laryngoscope 

51. Brantigan KO, Grow JB. Cricothyroidotomy elective 
use in respiratory problems requiring tracheostomy. J 
Thorac Cardiovasc Surg 1 976:7 1:72-81. 

52. Todres ID, Shannon DC. Monitoring occlusion and 
accidental intubation of tracheostomy tubes in children. 
Laryngoscope 1978:88:130-134. 

53. Lloyd-Thomas AR. ABC of major trauma: pediatric 
trauma — primary survey and resuscitation. Br Med J 

54. Orlowski JP, Elles NG, Aniin NP, Crumrine RS. Com- 
plications of airway intrusion in 100 consecutive cases 
in a pediatric ICU. Crit Care Med 1980:8:324-331. 

55. Gilmore BB, Micelson SA. Pediatric tracheostomy. 
Otolaryngol Clin North Am 1 986: 1 9(1 1: 1 4 1 - 1 5 1 . 

Reines Discussion 

Hurst: Dave Mulder and his asso- 
ciates in Montreal have described a 
newer technique, percutaneous endo- 
scopic tracheostomy for the ICU or 
the emergency department.' Their 
results (I think it was in 61 patients) 
have recently been presented in the 
Journal of Trauma — no complica- 
tions with only two failures that 
required conventional tracheostomy. 
Also, they're producing a movie of 
that same technique. Like many of 
the other techniques that we're doing 
now, this is an endoscopic technique. 
Lastly. I would like to review two 
studies that address the incidence of 
cervical spine injury. Kreipke and 
associates- evaluated the reliability 
of indicators to obtain cervical-spine 
films in patients with multiple organ 
system trauma. In a 1-year pros- 
pective study. 860 patients who pre- 
sented to a Level-I center were eval- 
uated in order to determine the signs 
and symptoms that would select 
patients at risk for cervical-spine 
injury. Clinical presentation of each 
patient was correlated with the pres- 
ence of C-spine fracture. Twenty- 
four patients (2.8%) had injuries 
demonstrated by plain film radiog- 
raphy. The incidence of fracture in 
536 asymptomatic patients was 4%. 

A significant likelihood of C-spine 
fracture was seen in patients with res- 
piratory compromise (100%), motor 
dysfunction (54.5%), and altered sen- 
sorium (8.9%). No fractures were 
seen in asymptomatic patients. There- 
fore, it is the conclusion of this par- 
ticular study and, certainly, my con- 
tention as well, that cervical-spine 
radiography should be performed in 
patients with abnormal neurological 
findings or symptoms referable to the 

In the study by O'Malley and 
Ross.' a more difficult question was 
addressed. That was, what is the inci- 
dence of cervical-spine injury in 
patients with craniocerebral injury? 
Previously, estimates of incidence of 
injurv' to the cervical spine among 
patients suffering blunt trauma to the 
head have varied widely. They have 
been reported as high as 20%. Since 
strict observation of cervical-spine 
precautions may delay attempts to 
gain control of the airway in a patient 
with intracranial injurv', the risk 
involved needs more exact definition. 
This study attempted to quantify that 
risk by examining records of 1,272 
consecutive patients with blunt injury 
admitted to a Level-I trauma center. 
Patients with serious craniocerebral 
injury were at no greater risk for 
injury to the cervical spine than 

patients without trauma to the head 
(1.8% vs 3.5%). Differences in these 
two percentages were not statistically 
significant. This study concluded 
that, although observance of cer- 
vical-spine precautions is para- 
mount, there may be times when this 
concern is superseded by the need to 
gain definiti\e airway control in a 
patient with injury to the brain. 

These two studies-' point out the 
fact that using reliable clinical indi- 
cators and exercising good clinical 
judgment will avoid missed injuries 
but, at the same time, maintain an 
acceptable standard of care. 

Lastly, studies regarding blood gas 
data with a variety of airway 
adjuncts should be done. Let us 
know how good or bad EGTAs or 
other airway management adjuncts 
are. It just so happens that I have a 
couple. Like many good studies, a 
good RCP and a good fellow are 
responsible for generation of most of 
these data (Jay Johannigman and 
Rich Branson). This suinmarizes our 
results in 160 patients in the recently 
completed prehospital care study, 
which is unpublished. You can read 
those for yourself. I would just like 
to point out the mean Pqt in the vari- 
ous groups. You can read those for 
yourself there. Table 1 looks at the 
preliminary data for the hospital 





period. Again, you can sec what the 
study looks like. We looked at ' "• 
patients in the HOA group separately. 
Those 12 patients had a mean Pco: of 
88 and a mean P02 of 14. I don't 
think we're ventilating patients 
nearly as well as we think we are 
with that device. 

1. Marelli D, Paul A, Manolides S. 
Walsh G, Odim JN. Burdon TA. et al. 
Endoscopic guided percutaneous 
tracheostomy: early results of a con- 
secutive trial. J Trauma 1990:30(4): 

2. Kreipke DL, Gillespie KR, McCarthy 
MC, Mail JT, Lappas JC, Broadie TA 
Reliability of indications for cervical- 


spine films in trauma patients. J Tra-uma 

1989:29(10): 1438-1439. 

3. O'Malley KF. Ross SE. The incidence 
of injury to the cer\ical-spine in 
patients with craniocerebral injury. J 
Trauma I988:28(10):1476-1478. 

Fanta: I wanted to follow up on the 
study that you mentioned about laryn- 
geal injury' and the reported high rate 
of laryngeal injury after a week or so 
of nasal or orotracheal intubation, 
and what the nature of those injuries 
were. I noticed that the ACCP con- 
sensus- suggested that some patients 
might remain intubated for as long as 
21 days before having to switch over 
to tracheostomv. and I think, as Ed 

Table 1. Preliminary Prehospital Airway Study 

Data for Patients with EOA as Final .Airway (n = 12) 

Age Time pH Pco: P02 


Data for Patients with Any Airway Other Than EOA (n = 148» 

Age Time pH Pcos P02 HCO," 

Data for All Patients with ET Tube a.s Final Airway (n = 103) 

Age Time pH Pc02 P02 HCO^ 

PatienLs/AII Modes of Airway Management (n = 160) 

Age Time pH Pco2 P02 














































































































































(Haponik) mentioned yesterday, 
intubation for as long as 3 weeks 
is common practice in a lot of 
medical ICUs. In my experience, 
one doesn't encounter significant 
laryngeal in-jury in as many as 
50% of patients in whom intuba- 
tion of this duration has occurred. 

1. Stauffer JL, Olson DL. Pens TL. 
Complications and consequences of 
endotracheal intubation and tracheo- 
tomy: a prospective study of 150 crit- 
ically ill adult patients. Am J Med 

2. Plummer AL. Gracey DR. Consensus 
conlerence on artificial airways in 
patients receiving mechanical ventila- 
tion. Chest 1989:96:178-180. 

Reines: Really the two best articles, 
neither of them prospectively ran- 
domized but both of them pros- 
pective, were Stauffer's article with 
Tom Petty' and Whited's article in 
Liii-yngoscope } They laryngoscoped 
every person that they extubated. and 
51% of the people had evidence of 
damage, but only 10% or so had 
severe damage in the early group. He 
had 3 groups — one group extubated 
at 5 days, one group at 6 to II days, 
and one group at greater than 1 1 
days. In all three groups, significant 
damage was \ isible on laryngoscopy 
in 5 1 % of the patients, but of those 
really only about 10%, or 7% of the 
whole population, had real, perma- 
nent problems. Our problem has 
been that we've had three cases of 
major aspiration pneumonia in older 
people who have been extubated 
after 14 days or so, and then have 
been fed 2 or 3 days later. When they 
were laryngoscoped. their cords were 
almost gone. So, I have a real prej- 
udice that there are populations, 
especially people moving around, 
who really damage their cords. 
You're never going to get a pros- 
pective randomized study, but surely 
if you laryngoscope every patient 
you extubate. it'll scare you. Maybe 
Dr Wilson has a comment on that. 




1. Stauffer JL. Olson DL. Petty TL. 
Complications of consequence ot 
endotracheal intubation and tracheo- 
stomy: a prospective study of 150 
critically ill adult patients. Am J Med 
19S I •.70:65-76. 

2. Whited RF. A prospective study of 
laryngotracheal sequelae in long term 
intubation. Laryngoscope 1984:94: 

Wilson: I think this is an unsettled 
issue and probably will never be set- 
tled — the preferred route and the 
time to tracheotomy. 1 think you 
have to interpret all these studies 
with the understanding that there are 
always a number of hidden \ariables, 
and you certainly have touched on a 
number of the variables: size of 
tubes, the trauma associated with the 
insertion of tubes, motion (which 
likely plays a part). When you look 
at invasive procedures, the experi- 
ence of the individual doing them, 
how skilled they are. and the fre- 
quency of error, the problem in look- 
ing at the time factor, of course, is 
one which has been complicated by 
the fact that you really can't predict. 
Significant numbers of individuals 
will have rather severe injury to 
laryngeal structures in a very short 
period of time, often in less than 24 
hours, but certainly within a couple 
of days. On the other hand, there are 
many anecdotal and even published 
experiences of individuals having 
tubes in place for weeks and months, 
with no injury. I think surveillance is 
the key, trying to assess as best as 
possible what the status of the upper 
airway is — obviously not a very sim- 
ple thing to do. Keeping that in 

mind, the pros and cons, the risks 
and dangers and hazards of doing 
a more in\asi\e procedure, is what 
needs to be focused on in tertns oi 
the time factor. 

Fanta: Is there any means to survey 
the larynx in an intubated patient? 
Wilson: Flexible fiberoptic visual- 
ization is one way. Direct visual- 
ization using a standard laryngoscope 
is a second means. Both of these have 
shortcomings in terms of how much 
you actually see. The only good way 
that I know of is to remove the tube, 
assess the larynx quickly , and replace 
the tube. This can be done, but of 
course it's a labor-intensive, high-risk 
proposition that really isn't very prac- 

Reines: That's the real problem as Dr 
Wilson says. In persons who have 
been intubated for a while, about 
whom we are concerned, we extubate 
over a bronchoscope, have the tube 
pulled out over the bronchoscope, 
and pull the bronchoscope back 
through the cords. If the cords look 
terrible, especially if this is in a bum 
patient or a patient with some other 
reason, we'll just slip the tube back 
in. If the cords look like hell, we go 
ahead and do a tracheostomy. But the 
reason the studies haven't been done, 
as Dr Wilson said, it means you have 
to do that to every patient you extu- 
bate to get the meaningful data. 
That's difficult even to get through 
your institutional review board, never 
mind through all the people that 
you're going to have to talk to. 
Haponilv: Our experience is very 
consistent with what you (Dr Reines) 
and Dr Wilson have alluded to. As 

part of our e\ aluation of our patients 
with burn-related upper airway 
obstruction. v\e perform serial stud- 
ies at the time of their extubalion. 
Anecdotally. and it is just an anec- 
dote, a nice, patent glottic chink 
around the sides of the tube seems to 
be a good sign, but it certainly does 
not assure that one can safely extu- 
bate that patient.' There are some 
instances in which you will see pro- 
lapse of still edematous mucosa, or 
even enveloping of the tube with no 
visible glottic or supraglottic lumen. 
An abbreviated, sometimes limited 
look before extubalion. then extuba- 
tion over the tube is the approach 
that we have taken in those indi- 
viduals. We have found it very dif- 
ficult to accurately predict success; 
one just has to be prepared for a very 
rapid response, if that initial impres- 
sion proves misleading. Dr Wilson 
has already alluded to some of the 
difficulties in trying to appropriately 
time extubations. It was speculated 
by some observers that the approach 
to laboriously reassessing the airway 
endoscopically. in some instances, 
actually led to more prolonged peri- 
ods of intubation because of some of 
the difficulties in interpreting ana- 
tomic signs in the presence of an 
already intubated airway. So. I think 
finding better ways to accurately pre- 
dict who will "fly' and better ways of 
evaluating the airway in this setting 
are very much needed. 

1. Haponik EF. Summer WR. Respira- 
tory complications in burned patients: 
diagnosis and management of inhala- 
tion injury. J Crit Care 1987;2: Ill- 



Thoracic Trauma 

James M Hurst MD 


Thoracic trauma ranks second only to head 
injur}' as the leading cause of death among trauma 
victims. Studies show that thoracic trauma 
accounts for one fourth of trauma deaths. The 
majority of these are the result of blunt injuries, pri- 
marily as a result of motor-vehicle accidents (auto- 
mobile, motorcycle, and pedestrian), falls, and 
crush injuries. The majority of the victims are 
male, with an average age in the mid-30s. The high 
incidence of associated injuries accounts for the 
majority of mortality and morbidity in this injury 
group. In most centers, isolated chest injuries occur 
in only 169r of patients, while 849^ have extrathor- 
acic injuries, and well over 5()9f have multi-system 
involvement. As.sociated injuries include head 
trauma (489^), extremity fractures (52%). intra- 
abdominal injuries (27%), and miscellaneous inju- 
ries (42% ).'-* 

Clearly, chest-wall injury is the most common of 
all thoracic injuries. Chest-wail injuries may range 
from simple rib fracture and costochondral separa- 
tions (Fig. 1) to more severe injuries resulting in 
Hail chest (Fig. 2), ruptured thoracic aorta, and 
even myocardial rupture. The degree of chest-wall 
trauma in a patient serves as a good indicator of the 
degree of force transmitted to underlying viscera. 

Dr Hurst was Director. Division of Tr;uini;i/Critical Care, and 
Professor of Surgery and Anesthesia. Depanment of Surgen,. 
University of Cincinnati Medical Center. Cincinnati. Ohio, 
when this paper was prepared. He is now Professor of Surgery 
and Anesthesia, and Director. Division of Trauma/Critical 
Care. University of South Florida. Tampa. Florida. 

A version of this paper was presented by Dr Hurst on October 
4. 1991. during the Respiratory Care Journal Conference on 

Emergency Respiratory Care held in Cancun. Mexico. 

Reprints: .latnes M Hurst MI). Room (ill2. Tampa General 
Hospital. Tampa FL 33601. 

Fig. 1 . Simple rib fractures. 

One important difference in this concept is seen in 
the pediatric population, where significant under- 
l_\ing injury can occur in the absence of rib frac- 
tures and Hail chest. This is due to the flexibililx of 
the thoracic cage in children. One study indicated 
that such underlying injuries occurred in 49% of 
pediatric patients."' The morbidity and mortality of 
chest-wall trauma are due primarily to the under- 
lying damage to pulmonary parenchyma and other 
intrathoracic structures.'"* rather than to flail or rib 

Fig. 2. Multiple rib fractures (flail chest). 




Differential Diagnosis in Trama 

The differential diagnosis of thoracic and any 
other injury should begin with the ABCs of resus- 
citation (Airway. Breathing, and Circulation, with 
hemorrhage control). Because it has been shown 
that 85% of patients with significant thoracic injury 
can be treated without surgery." it is of paramount 
importance to recognize those life-threatening inju- 
ries that must be treated rapidly and effectively. 
The life-threatening injuries that should be iden- 
tified in the primary survey are (1) airway obstruc- 
tion, (2) tension pneumothorax, (3) open pneu- 
mothorax, (4) massive hemothorax, (5) flail chest 
(with underlying pulmonary contusion), and (6) 
cardiac tamponade. Injuries considered potentially 
life-threatening are (1) pulmonary contusion, (2) 
myocardial contusion. (3 1 aortic disruption. (4) 
traumatic diaphragmatic hernia, (5) tracheo- 
bronchial disruption, and (6) esophageal injury.' 

Physical Inspection 

The "look, listen, and feel" technique, as advo- 
cated by the American College of Surgeons,** is a 
sound approach to the patient with thoracic injury. 
Observation is valuable in determining the overall 
ventilatory pattern of these patients. It will obvi- 
ously identify those patients with penetrating inju- 
ries likely to result in tension pneumothorax or 
those with wounds in a location to place them at 
risk for cardiac tamponade (Fig. 3). Many patients 
who are breathing spontaneously demonstrate para- 
doxical chest-wall motion at the time of presenta- 
tion. It should be remembered that intense inter- 
costal muscle spasm will splint even sizeable 
potential flail segments until muscle fatigue allows 
these segments to become mobile. Chest-wall 
defects (open pneumothorax) will be obvious at the 
time of presentation. Although tracheal deviation is 
one hallmark of tension pneumothorax, many 
trauma victims present with cervical immobiliza- 
tion collars in place, thus reducing the value of 
quick inspection of the position of the trachea. 

Subcutaneous emphysema can be readily felt 
and. if significant, can usually be easily seen (Fig. 
4). Unilateral subcutaneous emphysema may be a 
valuable sign, potentially indicating the side on 
which thoracic pathology may be located. How- 

Fig. 3. "Danger Zone" for penetrating thoracic wounds. 

ever, if a patient has been intubated in the field and 
is on positive pressure ventilation, subcutaneous 
emphysema is usually widespread and bilateral. 
The presence of massive subcutaneous emphysema 
should alert the examiner to the possibility of sig- 
nificant parenchymal disruption, as well as bron- 
chial and/or tracheal disruption. If the patient 
presents without subcutaneous emphysema but 

Fig. 4. Massive subcutaneous emphysema. 




develops this condition shortly after the initiation 
ol positive pressure ventilation, the aforementioned 
injuries should be ruled out. Rarely, bronchial dis- 
ruption may occur without disruption of the media- 
stinal pleura. Should this occur, subcutaneous 
emphysema will be confined to the head and neck. 
and pneumothorax will be absent. 

Auscultation remains a valuable tool in the diag- 
nosis of life-threatening chest injuries. The absence 
of breath sounds, alone or in combination with 
other signs of tension pneuniotlKMax. demands 
immediate intervention. The diagnoses of pneu- 
mothorax and/or tension pneumothorax remain 
clinical, not radiographic, diagnoses. The absence 
of breath sounds in combination with dullness to 
percussion may indicate significant hemothorax, 
alone or in combination with a pneumothorax. In 
the absence of penetrating injur\. the diagnosis of 
hemothorax is usually confirmed radiographically 
prior to treatment. 

Tabic 1. Adjunctive Radiographic Signs of Ruptured Tho- 
racic Aorta* 

Widened mediastinum 

Apical capping 

Fractures of first or second ribs 

Obliteration of contour of aonie knob 

Deviation of trachea to the right 

Left pleural effusion 

Hle\ ation and rightward shift of right main-stem bronchus 

Depression of left main-stem bronchus below 40° 

Obliteration of aorto-pulmonar\ \vindov\ 

Widening of paravertebral stripe 

* Adapted from information in Reference 7. 

undergo emergency contrast aortography (Fig. 6). 
Patients w ith first or first and second rib fractures 
should be e\aluated carefully for the other clinical 
and radiographic signs of thoracic aortic disruption 


Along with the lateral cer\ical-spine and peUic 
radiographs, the supine anterior-posterior chest 
radiograph is the mainstay of early trauma evalua- 
tion. The radiograph should be carefully inspected 
for signs of bony, pulmonary parenchymal, and 
major vascular in|ur\ . Of all the radiographic signs 
of suspected thoracic aortic disruption, a superior 
mediastinal width of more than 8 cm remains the 
best overall screen (Fig. 5 and Table T)'"'^ being 
the most valuable indicator of the need for thoracic 
aortography. With an appropriate mechanism of 
injury and the foregoing finding, the patient should 

Fig. 5. Widened mediastinum. 

Fig. 6 Traumatic disruption of thoracic aorta. 




F^arly Management 

The mainstays of early management of patients 
with hfe-threatening thoracic injury are airway 
management, adequate volume replacement, and 
the aggressive use of tube thoracostomy. In the 
absence of immediately available tube thor- 
acostomy, needle thoracostomy performed in the 
second intercostal space in the mid-clavicular 
line — or in the fourth intercostal space in the mid- 
axillary line — is indicated. Once needle thor- 
acostomy has been accomplished as a life-saving 
intervention, tube thoracostomy should follow 
promptly. The evolution of waterless chest- 
collection devices has, in most cases, obviated the 
need for the use of such devices as the Heimlich 
valve. Although some trochar-type devices are still 
being marketed, their use for emergency tube thor- 
acostomy is generally discouraged due to the unto- 
ward complications that can arise in the hands of 
unskilled users. 

Pathophysiology of Pulmonary Contusion 
and Flail Chest 

Fig. 7. Fracture of first right rib. 

(Fig. 7). Other work has correlated the extent of 
scapular fracture with associated underlying vis- 
ceral injury (Fig. 8)." 


Fig. 8. Grade IV scapular fracture. 

Although much space could be given to the dis- 
cussion of the pathophysiology of a variety of tho- 
racic injuries, it is appropriate for this paper to con- 
centrate on the pathophysiology of pulmonary 
contusion and tlail chest. 

Several mechanisms have been proposed as pro- 
ducing the injuries seen with pulmonary contusion. 
The first is an implosion effect, which results from 
an abrupt rise in the airway pressure and produces 
disruption of the alveoli. A spallation effect, in 
which a concussive wave partially reflects off a liq- 
uid-gas interface, has also been shown to disrupt 
alveoli.'- '"^ These injuries are generally seen with 
higher impact velocities.'-'^ At lower impact 
velocities, disniption of alveoli from bronchioles is 
due to an inertia! effect in which differential rates 
of tissue acceleration-deceleration cause separation 
of these structures. Lastly, a direct crush injury can 
be seen when the impact causes significant chest- 
wall deformity. 

Grossly contused areas demonstrate subpleural 
and parenchymal hemorrhage, which correspond 
microscopically to ruptured pulmonary arterioles 
and alveoli, with intra-alveolar hemorrhage and 




interstitial and peribronchial edema. Areas of ate- 
lectasis alternating with areas of gas trapping can 
also be seen. Alterations in pulmonary capillar) 
permeability are initially seen in the contused seg- 
ment, but they can also progress to the uninjured 
lung after several days. This has been speculated to 
be due to injury of the pulmonary endothelium, 
with activation of complement and humoral and 
cellular mediators.'^ A generalized inflammatory 
response may then ensue and result in increased 
capillary permeabi!il\ in the uninjured lung (adult 
respiratory distress syndrome, ARDS). In addition 
to alterations in capillary permeability, decreased 
production of surfactant has been demonstrated 24 
U) 48 hours following injury. "' As would be antici- 
pated, the resulting physiologic changes include 
decreases in functional residual capacity, total lung 
capacity, and lung compliance. Increases in work 
of breathing, airway resistance, pulmonary vascular 
resistance, and intrapulmonary shunt from ventila- 
tion-perfusion mismatch have also been noted."' 
The paradoxical motion of the flail segment, other 
than presenting problems in pain management, is 
not usually a major contributor to morbidity. 


As has previously been stated, tlail chest alone 
does not mandate treatment by tracheal intubation 
and mechanical ventilation (MV).'^-" However, 
because many of these patients have associated 
head injury, early airway control and MV may 
indeed be required. In an unpublished study, we 
have conclusively shown that prehospital ventila- 
tion via methods other than tracheal intubation 
results in unpredictable and unacceptable gas 
exchange. The use of self-intlating resuscitation 
bags is a time-honored and, for the most part, 
acceptable means of providing positive pressure 
ventilation. In the field, these devices have the 
advantages of being reliable, portable, and easily 

Transport Ventilation 

management (respiratory therapists).-' We con- 
cluded that small, pneumatically powered or elec- 
tronic transport ventilators provide predictable and 
reliable gas exchange for critically ill patients 
requiring even high levels of ventilatory support. 
These de\ices also free the therapist to perform 
other duties. 

While skilled support is available for intra- 
hospital transport, the preho.spital environment is 
quite another matter. An equally important ques- 
tion lo answer is. Are transport \entilators reliable 
in the field? Even if they are pro\ en to be reliable, 
can prehospital care personnel be taught to use 
these devices safely and effectively? 

The answer to both questions is a resounding 
Yes. We have conducted two studies addressing 
both of these questions.-' -- In the initial study,-' 
two paramedic life squads were taught to use an 
oxygen-powered transport ventilator. The required 
training time was acceptable. Before the \entilators 
were placed in the field, the paramedics were 
extensively drilled in their use with a test lung. The 
study design was simple. The patients were under- 
going cardiopulmonary resuscitation, with ventila- 
tion provided with a self-inflating resuscitation bag 
or the gas-powered transport ventilator. We studied 
28 patients, 14 ventilated by bag and 14 by trans- 
port ventilator. Arterial blood-gas samples were 
obtained within 5 minutes of a patient's arrival in 
the emergencN department. There was no statis- 
tically significant difference in any measured \ar- 
iable between the resuscitation-bag and the trans- 
port-ventilator groups. Adequate ventilation and 
oxygenation were accomplished, freeing the par- 
amedics to perform other important tasks. In no 
case was there a ventilator failure. 

.After this pilot study, paramedic units were pro- 
vided with either oxygen-powered or electronic 
transport ventilators for cardiopulmonar\ arrest. To 
date, data from 160 patients have been analyzed. -- 
From this information we have concluded that the 
most effective method of ventilation during trans- 
port in the field and for diagnostic studies in the 
hospital is MV \ ia an endotracheal tube. 

In a well-controlled study examining the effi- 
cacy and reliability of transport ventilators in the 
intrahospilal environment, we noted unintended 
hyperventilation by individuals skilled in airway 

Other Aspects of Treatment 

For patients not requiring early endotracheal 
intubatit)n, a variety of treatment support options 


RESPIRA rOR^' C ARF, • Il'LY "92 Vol 37 No 7 


are available. The use ol enineiuional Dwgeii- 
delivery devices is the pret'ened initial option 
because of their availability and ease of use. Along 
with oxygen delivery, appropriate analgesia is of 
utmost importance. The use of parenteral opioids 
may be appropriate for the young, healthy trauma 
victim without a variety of underlying medical 
problems. On the other hand, aggressive use of opi- 
oids, even in this group of patients, may preclude 
weaning from MV secondary to depression of the 
ventilatory drive. We advocate the aggressive use 
of thoracic epidural analgesia with opioids and/or 
local anesthetics in the hospital setting.''-'' We 
have demonstrated this to be an effective method of 
treatment alone, or in combination with continuous 
positive airway pressure (CPAP) by mask.-' In 
older patients, this is the preferred method of pro- 
viding analgesia due to their sensitivity to parenter- 
ally administered opioids. It should be emphasized 
that mask CPAP therapy is indicated for mild to 
moderate hypoxemia, and not for hypercapnia. A 
functioning nasogastric tube or gastrostomy tube is 
necessary to prevent gastric distention. The CPAP 
mask is contraindicated in the presence of basilar 
skull fracture or inability of the patient to protect 
his airway. Reviews of CPAP are available and 
should be refeired to.-''-'' 

If patients have been intubated for airway man- 
agement secondary to a central nervous system 
injury, little option may be available as far as ven- 
tilatory modality is concerned. Controlled MV with 
a minute volume large enough to provide an initial 
PaCO: of 28-32 torr should be employed.-*^ As intra- 
cranial compliance improves, attention may then be 
turned to management of coexisting pulmonary 

If increased intracranial pressure is not part of 
the initial injun,' complex, interventions to treat pri- 
mary pulmonary dysfunction should be initiated. It 
is our belief that partial ventilatory support is pref- 
erable to controlled mechanical ventilation (CMV). 
Almost invariably, we use thoracic epidural anal- 
gesia in conjunction with partial ventilatory sup- 
port. Whereas intermittent mandatory ventilation 
(IMV) was the mainstay of therapy in our institu- 
tion for years, the microprocessor-based ventilators 
now provide a whole new horizon for treatment 
options. Currently, pressure support ventilation 
(PSV) is our initial treatment modality.-'' 

Reducing Cost of Breathinj> via 
Mechanical Ventilation 

Although we use indirect calorimetry to estimate 
optimal calorie replacement as well as calorie- 
nitrogen ratio, we have not used this method to 
determine reduction in the oxygen cost of breath- 
ing. Our approach has been to increase the level of 
PSV in S-cm-H.O increments above baseline pres- 
sure. Target end points are the best decrease in 
spontaneous breathing rate and the best aug- 
mentation of tidal volume (usually 10-12 niL/kg of 
body weight). If this end point, termed PSV,,,^, by 
Maclntyre,"*" corresponds to the patient's peak 
inspirator}' pres.sure on CMV, a period of CMV is 
prt)bably wananted. The goal of employing partial 
ventilatory support — other than to decrease any gas 
flow through bronchopleural fistulae and to 
improve overall V/Q — is to avoid long periods of 
respiratory muscle rest. It has been shown that such 
long periods of CMV lead to respiratory muscle 
atrophy and to a decrease in high-energy inter- 
mediates in these muscles.'" 

In order to achieve the "ideal" PSV breath con- 
tour, attention may have to be paid to the inspir- 
atory side of the curve as well as to the expiratory 
side. We have noted that by adjusting flow during 
inspiration we can achieve much better patient- 
ventilator synchrony.'' This approach is par- 
ticularly useful in difficult weaning situations. 

Pres.sure controll ventilation (PCV) can also be 
employed as a partial support modality.'- Our 
approach has been to use PCV when CO; retention 
is a problem or when tidal volumes have been 
inconsistent. PCV is also useful in patients with a 
central neurogenic ventilatory pattern secondary to 
a closed-head injury. Frequently in these instances 
the level of PEEP can be reduced, as well. 

Finally, specialized treatment modalities such as 
synchronous independent lung ventilation (SILV),'-' 
high-frequency ventilation (HFV)," or PCV'- are 
available when patients fail to respond to conven- 
tional ventilatory modalities. We feel that these 
specialized modalities should be used only in ter- 
tiary referral centers where the treatment team con- 
sists of physicians, nurses, and respiratory ther- 
apists who are skilled in their use. We have 
employed HFV in patients who did not respond to 
conventional ventilation — and because of its pur- 




posed action — in patients with dense unilateral con- 
tusions. We have been particularly aggressive in 
using HFV preferentially in patients with sig- 
nificant pulmonary dysfunction and severe closed- 
head injury when intracranial pressure has been dif- 
ficult to manage by conventional medical inter- 
ventions.'"'* In this setting, we have demonstrated 
that mechanical hyperven-tilation can be accom- 
plished with approximately half the peak inspir- 
atory pressure, and the level of oxygenation can be 
maintained v\iih approximately half the level of 
PEEP required with conventional ventilation — but 
at the same mean airway pressure.'^ The possible 
benefit lies in not impeding cerebral venous return 
as a consequence of ventilatory support. 


As a result of direct injury to the pulmonary 
parenchyma or secondary to MV, pulmonary bar- 
otrauma is a common finding in most critical care 
units. Much of the observed barotrauma is of the 
inconsequential variety (subcutaneous emphy- 
sema). Other forms (such as tension pneumothorax, 
pneumopericardium, bronchopleural fistula, and 
even pneumoperitoneum) may be life-threatening. 

Berg et al investigated the mechanisms ot pneu- 
mothorax during MV in a feline model.'''' Animals 
received either tracheostomy or tracheal intubation. 
Dye was placed in the cervical fascial planes, and 
catheters were placed subcutaneously to simulate 
air entry into fascial planes during and after tra- 
cheotomy. The placement of catheters in super- 
ficial planes resulted in subcutaneous emphysema 
confined to the neck, axillae, and chest wall. Cath- 
eters were then placed in the middle layer of deep 
cervical fascia, which surrounds the thyroid gland, 
trachea, and est)phagus. and which is contiguous 
with the fibrous pericardium inferiorly. Air injected 
into this space spread to the bifurcation of the tra- 
chea at its lowest point: therefore, it regularly pro- 
duced pneumomediastinum but failed to produce 
pneumothorax. In order for this route of air entry to 
produce pneumothorax, there must be a violation of 
the mediastinal pleura. While this may occur as a 
direct result of penetrating or blunt trauma, it is 
much less likely to occur spontaneously. 

Large tidal volumes and high peak airway pres- 
sures have been implicated by Berg et al in the eti- 

ology of pneumothorax during MV." Intubated 
animals were studied with computed tomographic 
(CT) scans to determine the mechanism of injury 
resulting in pneumothorax. Selective right main- 
stem intubation was performed, and peri\ascular 
emphysema was noted prior to the development of 
pneumothorax. Macklin and Macklin have theo- 
rized that this perivascular emphysema is likely the 
direct manifestation of rupture of marginal (peri- 
vascular) alveoli.'*" Free air dissects proximally to 
the mediastinum to produce pneumomedia-stinum 
and pneumothorax secondarily. Therapy for this 
form of barotrauma is pre\enti\e if at all possible. 
Failing this, a high index of suspicion for patients 
at risk is essential. The mainstay of therapy is tube 

Pneumopericardium is frequently seen in the 
patient with multiple-organ-system injury. For the 
most part, it is inconsequential in terms of the 
patient's hemodynamics. Rarely, this form of baro- 
trauma may mimic cardiac tamponade,"* especially 
in children. Not all the classical findings associated 
with cardiac tamponade may be present. The com- 
bination of extensive subcutaneous emphysema, 
previously noted pneumomediastinum, or sudden 
hemodynamic deterioration in the absence of ten- 
sion pneumothorax should alert one to the possibil- 
ity of tension pneumopericardium. There is essen- 
tially no time for diagnostic evaluation. Emer- 
gency treatment consists of pericardiocentesis. If 
air is obtained and hemodynamic improvement is 
noted, an indwelling catheter may be left in situ. 
Rarely, this condition may require creation of a for- 
mal pericardial window. 

Pneumatocele formation results from the collec- 
tion of gas beneath the visceral lung pleura. While 
this complication is common in the neonatal and 
pediatric populations, it occurs less frequently in 
the adult. ^'' Gas trapping, inspissation of secretions, 
or rupture of respiratory bronchioles, alveolar 
ducts, or alveoli are all possible mechanisms."* 

Several complications may arise as a result of 
pneumatocele formation. Pneumatoceles may rup- 
ture into the free pleural space, resulting in tension 
pneumothorax. Because gas tlow in these areas is 
by definition stagnant, secondary infection may 
occur. This may result in localized abscess forma- 
tion, or — if they rupture in the pleural space — frank 
empyema may result. 




Treatment iiuist be iiidi\idiiali/ed but ei^msists of 
prevention if possible. Onee pneumatoceles are 
noted, they should be followed for the onset of 
complications. If they remain stable, they usually 
can be expected to resolve with time. If they 
become secondarily infected, frequently they can 
be drained percutaneously. Because many of these 
patients may ha\e a multitude of abnormal findings 
on chest radiograph, CT or ultrasound investi- 
gations may be needed to precisely locate the 

Bronchopleural fistula may occur as a result of 
direct trauma or of MV. The primary defect results 
in preferential gas flow through the fistula. If there 
is any significant unilateral decrease in compliance, 
the defect may result in almost total loss of tidal 
volume through the fistula. Treatment is aimed at a 
more even distribution of the mechanically deliv- 
ered tidal volume. A variety of modalities of MV 
can be employed to facilitate this therapeutic end 
point. Several general supportive measures that 
have been suggested are using the lowest rate of 
mechanical breaths compatible with adequate alve- 
olar ventilation, avoiding or correcting respiratory 
alkalosis, minimizing inspiratory time, using the 
minimum PEEP necessary to achieve an oxy- 
hemoglobin saturation of 90%, employing the low- 
est possible chest-tube suction compatible with full 
lung expansion, avoiding body positions that 
increase air leak, and sedating when patient agita- 
tion increases air leak.'"' More exotic measures 
have included intermittent chest-tube occlusion,"*' 
SILV.'-' and HFV.''' Notably absent from this list is 
surgical intervention directed at the fistula itself, 
because this approach is associated with a high 
incidence of recurrence and an unacceptably high 
operative mortality. 

Rarely considered in most discussion of pul- 
monary barotrauma is pneumoperitoneum. Much 
like other fonns of barotrauma, it is for the most 
part inconsequential. It is a not infrequent com- 
plication of MV.'*- While ruptured hollow viscera 
and postsurgical changes account for 907c of all 
cases of pneumoperitoneum, Hillman found that 
10% were due to complications of mechanical ven- 
tilation."*- Table 2 outlines the significance of a 
variety of ventilatory parameters in the etiology of 
28 cases of pneumoperitoneum reviewed by Hill- 

Table 2. Ventilatory Parameters in Etiology of 28 Cases of 

PIPt (cm H:0) 
Not doeuiiiented 



> 15 

Not documented 

Tidal volume (niL) 
700- 1 .000 

> 1.000 

Not documented 

Number of Patients 


* Adapted from information in Reference 42. 

t PIP = peak inspiratory pressure; PEEP = positive end-expiratory 

Rarely, massive pneumoperitoneum may result 
in both respiratory and hemodynamic compromise. 
It may be associated with a profound restrictive 
effect due to the upward displacement of the dia- 
phragiB. Hemodynainic manifestations include 
poor venous return, with decreased cardiac output 
and profound oliguria. This is an interesting phe- 
nomenon originally thought to be due to direct 
compression of the renal arteries. While this does 
occur to .some extent, the major etiologic factor is a 
marked increase in renal-vein vascular resis- 
tance."*''"'^ In the absence of other findings, this 
must be considered when respiratory or hemo- 
dynamic compromise is noted. Documentation 
rests with the determination of intra-abdominal 
pressure. This may be readily accomplished by 
measuring urinary bladder pressure via the in- 
dwelling urinary catheter. Values above 25 mm Hg 
deserve therapeutic intervention. Needle catheters 
or closed-suction drains are appropriate means to 
obtain peritoneal decompression. Repeated deter- 
minations of intra-abdominal pressure are nec- 
essary to document therapeutic benefit. 




Long-Term Effects of Thoracic Injury 

Although it is readily apparent that thoracic 
injury is a common problem, it is less well appre- 
ciated that only 509f of patients with significant 
thoracic injury return to gainful employment. "'^""'^ 
Chronic pain from chest-uail deformity, and 
restrictive and obstructive ventilatory defects, 
along with the presence of underlying medical 
problems, contribute to this morbidity. This fact 
underscores the need for early, aggressive man- 
agement, as well as a full-service rehabilitation pro- 
gram. This program should be instituted as soon as 
the patient's clinical status permits. 


Thoracic trauma is a common problem in 
patients with multiple-organ-system injury. Most 
problems can be treated v\ ithout surger>'. It is there- 
fore important to be able to recognize the immedi- 
ately and potentially life-threatening injuries. It is 
likewise important to recognize the fact that man- 
agement of the airway and of ventilation is a main- 
stay in the management of thoracic injury. Use of a 
team — consisting of physicians, critical care 
nurses, and respiratory therapists — is essential in 
the modem-day care of these patients. 


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Hurst Discussion 

Reines: What kind of pain medicine 
are you using? Are you using tho- 
racic epidurals like we are. or are you 
using patient-controlled analgesia 
(PCAs)? Also, what percentage of 
your patients with pulmonary contu- 
sions or flail chest are you having to 

Hurst: First of all. I think if you have 
a good pain service, which we do. 
they are invaluable in helping care 
for this type of patient. We use a 
combination of epidural tnorphine. 
Demerol, or fentanyl. depending on 
the patient and the preference of the 
anesthesiologist. Most of the time we 
will add Marcaine (bupivacaine) to 
that cocktail. This usually results in 

good pain control. If we use that reg- 
imen plus graded application of ven- 
tilatory support (whatever oxygen 
delivery device you like, good chest 
physiotherapy, and. if the patient 
becomes hypoxemic, progression to 
CPAP mask, then to intubation), we 
only have to intubate — what would 
you say. Rich (Branson)? — maybe 
20-25% of the patients who don't 
have to be intubated for another rea- 
son (eg. a trip to the operating room)? 
We have really obviated the need for 
intubation in a majority of those 

Weaver: To answer your question, 
for chest tubes. Heimlich valves, 
whate\er: in Salt Lake City, for hel- 
icopter transport we generally use 
chest tubes with Heimlich valves 

because the tubes were placed in the 
field or in another facility, and we're 
in a hurry to get the patient back to 
our facility. For fixed-wing trans- 
port, generally we're transporting an 
ARDS patient who already has chest 
tubes and Pleur-Evac water seals. 
Those tubes are placed to suction 
during transport in the ARDS pop- 
ulation because we've encountered 
substantial pneumothoraces that 
have been of considerable hemo- 
dynamic con.sequence. So. we feel 
\ery strongly about placing those 
tubes to suction during transport. 
The next point, you showed aci- 
demia with mechanical ventilation 
in trauma patients during prehospital 
care or upon entry into hospital. Can 
you tell us what sort of minute ven- 




tilation you were delivering lo those 
patients in that study'.' 
Hurst: I showed that acid-base data 
to make a plea. Our survivors had a 
pH greater than 7.15 and the non- 
survivors less than 7.09. If you have a 
patient with a Pco: of 88, you ask 
yourself. "If they were ade(.|uatcl\ 
\entilated. would that put them o\er 
that pH level and perhaps push them 
into the survivor category'"" 1 don't 
kniiu. I hope so. If you look at the 
Pfo: in those patients who were on 
mechanical \entilation — again, cor- 
rect me if I'm wrong. Rich (Bran- 
son) — the average P^co; was right 
around 40. We were certainly pro- 
viding adequate minute ventilation. 1 
don't think we're worried about that. 
If vou look at the acid-base data on 
patients regardless of their type of 
airway, they all had base deficit on 
the average of -12. if my memory 
serves me correctly. That means 
(again, as you and I would think 
intuitively) they all have a significant 
metabolic acidosis. Ought we to he 
treating that metabolic component'.' I 
guess my bias is that we probably 
should be. To get back to your other 
question, I wasn't advocating the var- 
ious types of chest-tube-valve de- 
vices at all. We have gotten away 
from using the Pleur-Evacs, only 
because they're water-containing. 
Our flight service is employing 
waterless devices. They are very 
small — only about half the si/e of the 
Pleur-Evac. No matter what position 
you put them in, you'll still he able to 
achieve adequate suction drainage. 
Yes, we try to keep all our devices 
during transport and. ceriainlv. in the 
operating room on suction. I, like 
you, have seen too many pneu- 
mothoraces that are hemodynam- 
ically significant not to keep them on 

Porter: What is the frequency of 
other myocardial abnormalities that 
you've seen — including tricuspid 
valve, right-atrial appendage tears. 

and myocardial contusion — in your 

Hurst: The frequency of injury'.' We 
looked at the results of radionuclide 
scanning in a group of patients 
(unpublished data). More recently we 
have switched to transthoracic or 
transesophageal 2-dimension echo- 
cardiographv . Interestingly enough, 
the incidence is very difficult to 
ascertain. If you look for abnormal- 
ities, you're going to find them. I 
don't think there's any question about 
that. 1 think the more important ques- 
tion is. "What abnormalities are you 
going to find that are going to be 
hemodvnamically significant, require 
therapv . or have impact on therapy'?" 
Interestingly enough, if you look at all 
the screening tests. EKG is still rea- 
sonably important. We found that no 
patient who had a normal EKG had a 
hemodynamicall) significant abnor- 
mality. Only patients who had abnor- 
mal EKGs upon admission had some 
abnormality. If I remember our data 
coirectly, it was around 5%. As many 
ot you know, a number of years ago 
we treated myocardial contusion just 
like an MI (myocardial infarction). 
We tried to diagnose it like an MI; 
but. because it's not the same 
pathophysiology, you can't diagnose 
it like an MI, and you really can't tell 
a 35- or 40-year-old individual who 
is gainfully employed that he or she 
can't work for (S weeks. Those with 
myocardial contusion do not have the 
same dysrhythmia potential as a 
patient with an MI. Myocardial con- 
tusion doesn't have an ischemic eti- 
ology. They may have edema around 
a conduction bundle. The extent and 
duration of the arrhythmia is directly 
proportional to the impact velocity. 
Porter: So, you're saying that myo- 
cardial contusion is more frequent 
than a Hail tricuspid valve. 
Hurst: We have not seen an isolated 
tricuspid valve abnormality. Myo- 
cardial contusion is more frequent, 
although the early literature would 
have you believe it's predominantly 

right ventricular because of the pres- 
entation of the right ventricle to the 
injuring force. I think there are good 
data to support the fact that multiple 
chambers can be involved because 
of the way the force is transmitted. It 
is not just the result of direct injurv.' 

1. Hursl JM. Johannigman }.\. Cardiac 
trauma. In: Gerson MC. ed. Cardiac 
nuclear medicine. New 'York: Mc- 
Graw-Hill. 1991:539-549. 

NemirofT: In your follow-up with 
these. I noticed there were abnormal 
pulmonary functions and probable 
anatomic differences as these 
patients healed. One of the common 
questions in this young male popula- 
tion is. "Can I go back to scuba div- 
ing'.'" Do you have any experience, 
positive or negative, with that — or 
does anybody else'.' 
Hurst: Not in this particular group 
of patients, but we did look at pul- 
monarv functions in the group of 
patients undergoing high frequency 
ventilation. These people were 
sometimes hard to get back for pul- 
monary function testing (PFT). They 
fell into two groups — those patients 
who did not develop a nosocomial 
pneumonia and who did. If 
you looked at PFTs of those not sec- 
ondarily infected, thev liad normal 
PFTs. Those who developed nos- 
ocomial pneumonias had a restric- 
tive and an obstructive defect, w hich 
was not terribK evident at rest but 
which did become more ev ident dur- 
ing exercise. The young woman hit 
by the pickup truck, was followed 
extensively. She had been on 100% 
oxygen for about 6 weeks, on high- 
frequency ventilation for that period 
of time, and had had Pq.s as low as 
27-.^0 before she finally improved. 
Her last PFTs were about 60 to 70% 
of normal with exercise. I guess mv 
feeling is that they probably could 


RESPIR.ATOR>' C.ARF • JULY '92 Vol 37 No 7 


return to that level. 1 would really 
limit patients only by how symp- 
tomatic they are and what their per- 
foniiance level is. 

Reines: I just went through that w ith 
two patients who are scuba divers. 
We retested them at 6 weeks, when 
we felt the pain was down, and made 
a determination at that time. At 6 
weeks I said. "I don't even want you 
going underwater at all." When we 
did their pulmonary functions at 6 
weeks, both of them were sig- 
nificantly decreased because of 
mechanics and pain. I wouldn't let 
anybody scuba di\ e in less than prob- 
ably 2 months, but snorkeling is dif- 
ferent because you don't have to 
worry about the pressure. 
Weaver: The major concern in scuba 
diving is regional gas trapping, and I 
wonder about the sensitivity of PFTs 
for regional gas trapping. I've evalu- 
ated several patients with traumatic 
thoracic wounds for fitness to dive. 
Generally. I'll use PFTs. niavbe 

they're normal, then I'll go on to a 
xenon-gas washout. l(X)king at wash- 
out time. I'm still not sure if that's an 
acceptable test because as a physi- 
cian you're being asked. What is the 
risk of arterial gas embolism? There's 
a baseline frequency, as it were, of 
arterial gas embolism in the diving 
population, with about 100 cases per 
year occurring in the United States:' 
so. there are some liability issues that 
you may want to think about before 
permitting the person to sport scuba 
dive. Most times I err on the side of 
being very conservative when I'm 
forced to make those statements, 
when I feel that even under the best 
circumstances the data are somewhat 
limited, and I'm not sure I can ade- 
quately make the appropriate rec- 

Dovenbarger J A. coordinator. 1989 
report on diving accidents and fatal- 
ities. Durham NC: Divers Alert Net- 
work. 1991:49. 

Haponik: What's the frequency of 
nosocomial pneumonia in chest 
trauma patients? And. given the high 
frequency of abnormal chest x-rays 
and airway colonization, how do 
you diagnose it in your population? 
Hurst: Probably the true frequency 
is that the more you look for it. the 
higher it's going to be. I guess my 
current mind-set is that the best way 
to diagnose it is either by using a 
plugged-core brush or a deep-brush 
technique to look for intracellular 
organisms. If you employ this tech- 
nique, you're probably going to find 
it around 20-25'* of the time. If you 
just use the presence of polymorpho- 
nuclear leukocytes in the sputum, 
you're going to find an awful lot in 
the population that we look at. I 
don't think that that's a very good 
way to diagnose it. 
Haponik: Do you withhold anti- 
biotics pending the availability of 
that information? 
Hurst: Yes, we do. 



Hyperbaric Treatment of Respiratoiy Emergencies 

Lindell K Weaver MD 


Hyperbaric oxygen (HBOi) is 100% oxygen 
(O2) inhaled by individuals exposed to greater than 
atmospheric pressure.' By definition. HBO^ does 
not include the use of topical, or limb-chamber, 

The history of hyperbaric air therapy dates back 
over 300 years/' and HBO. was first used more 
than 100 years ago.' In the early 1960s. Brum- 
melkamp et al reported that HBO2 could sig- 
nificantly alter the outcome in anaerobic infec- 
tions.'* and Boerema et al reported that life could be 
adequately supported by HBO; in the absence of 
hemoglobin." Following these reports, interest in 
clinical HBO2 therapy increased quickly in the 
USA. Several research centers were constructed in 
the 1960s, and HBO. was touted as an incredible 
new therapy that would prove useful for a myriad 
of diseases.'' As is often the case. HBO2 did not 
turn out to be a panacea, and the medical com- 
munity quickly lost interest. However, the past 15 
years have seen a resurgence of interest in HBO2. 
Whereas in 1976 there were only 37 clinical HBO2 
units in the USA. by 1990 there were more than 
200 7.8„i* The contemporary indications for HBO2 
are shown in Table 1. 

Dr Weaver is Medical Director of Hyperbaric Medicine and 
Co-Director of Critical Care. LDS Hospital; and Assistant Pro- 
fessor of Medicine. University of Utali Medical Center — Salt 
Lake City. Utah. 

A version of this paper was presented by Dr Weaver on Octo- 
ber 4. 1991. during the Rf-:si>irat()R\ Carf-; Journal Confer- 
ence on Hniergency Respiratory Care held in Cancun. Mexico. 

In this paper I discuss how HBO; is delivered, 
its physiologic effects, the risks, the use of HBO2 
in emergency care, chamber operation, outcome 
studies, and the role of the respiratory care practi- 
tioner in the expanding field of HBO2. 

Table 1. Indications for HBO. Therapy* 

Emergency Conditions 

Air or gas embolism 

Decompression sickness 

Carbon monoxide poisoning and/or cyanide poisoning 

Gas gangrene 

Necrotizing soft-tissue infections 

Acute traumatic ischemia, crush injury, and compartment 

Compromised (ischemic) grafts and flaps 
Exceptional blood loss 

Chronic Conditions 

Enhancement of healing in selected problem wounds 
Refractory osteomyelitis 
Radiation necrosis 

♦Adapted from Reference 1 . 

How Is HBO, Delivered? 

Patients receiving HBO2 are treated in either a 
multiplacc (multi-person) h>perbaric chamber or a 
monoplace (one-person) chamber. Muitiplace 
chambers generally are of the double-lock design 
(Fig. 1 ). The two interconnected chambers can be 
operated independently, allowing attendants to 

*A current listing o( h\ pcrbaric chamber locations is available 
from the Undersea and H\perbaric Medical .Socielx. 9650 
Rockville Pike. Bethesda MD 21201 (.^Ol/.'iTI-ISSl ), The Div- 
ers' Alert Network (DAN). PO Box 3823. Durham NC 27710 
(919/684-8111). is also a resource regarding chamber loca- 
tions, especially in the event of a diving emergency. 




enter and leave the treatment chamber via the sec- 
ondary chamber without depressurizing the treat- 
ment chamber. Miiltiplace chambers are tilled with 
air, and the patient breathes 101)% Ot via a mask, 
endotracheal tube, or hood placed over his head. 

^t^ . .% '^^Vj^l 


^L i .1HH 

Fig. 1. A multiplace hyperbaric chamber. (Photograph 
courtesy of Reimers Engineering Inc, Alexandria, Vir- 

Hamilton compared multiplace and monoplace 
chambers, citing the advantages and disadvantages 
of each.'' The obvious advantage of a multiplace 
chamber is the large size of the treatment compart- 
ment, pemiitting caregivers ready access to 
patients. The disadvantages of multiplace facilities 
compared to monoplace charnbers are their size 
and cost. Multiplace chambers are heavy and gen- 
erally require placement on a ground floor. This 
may force location of the chamber some distance 
from emergency or critical care facilities. Fur- 
thermore, multiplace chambers are more expensive 
to operate and are inefficient unless the number of 
treatments per day is high. A multiplace chamber 
requires at least two attendants, one inside and one 
outside the chamber, to treat even a single patient. 

Most hyperbaric treatments in the United States 
are delivered in monoplace hyperbaric chambers,'" 
which are generally filled with 100% oxygen. 
These chambers are made of Plexiglas (Fig. 2). The 
patient lies supine inside the chamber, and com- 
munication is accomplished via an intercom and 
observation. The primarv ad\ antages of the mono- 
place over the multiplace chamber are its smaller 
size and lower operating cost. 

Physicians have expressed concern about mono- 
place chamber therapy because the attendant does 
not have hands-on access to the compressed 
patient." It may be optimal that HBOi patients 
have attendants immediately available to render 
hands-on care during the HBOt .sessions, but this 
certainly is not absolutely necessary. Most HBOi 
treatments are provided to outpatients who are not 
critically ill.'" 

It may be easier to treat critically ill patients 
with HBO: in multiplace chambers because hands- 
on care can be provided in that setting. Such 
patients require meticulous attention to detail 
regarding intravenous catheters, endotracheal 
tubes, chest tubes, and surgical drains. These pro- 
cedures must be performed prior to enclosure in a 
monoplace chamber,'-"''* but in a multiplace cham- 
ber they may be performed at any time. There is 
considerable experience at some HBO^ centers in 
the care of critically ill patients in monoplace 
chambers.'-""' Injured divers can be adequately 
treated in them.''"''' An editorial statement from the 
Divers" Alert Network recommends that diving- 
accident patients be referred to the nearest appro- 
priate recompression chamber, including mono- 
place facilities if they have staff who are knowl- 
edgeable about diving accidents, as delays in 
treatment adversely affect outcome.-" 

Respiratory therapists working in hyperbaric 
medicine need to be knowledgeable regarding 
mechanical ventilation of patients during HBOi 
therapy. Ventilators used in the hyperbaric environ- 
ment may exhibit significantly altered perfor- 

^» - '^Kj^ 





...^m^ .» . 



IP-- ^ 

P • 1 

Fig. 2. A monoplace hyperbaric chamber. (Photograph 
courtesy of Sechrist Industries, Anaheim, California.) 




mance."' " Only a few ventilators are adequate for 
inultiplace-chamber use.-' Modifications to en- 
hance ventilator performance may be required.-' In 
a study by my group, mechanical-ventilator testing 
in the monoplace chamber demonstrated significant 
reductions in tidal volumes during chamber com- 
pression in test lungs with normal and reduced 
compliances.-- We therefore recommend that astute 
attention to detail be employed with any mechan- 
ically ventilated patient in the hyperbaric environ- 
ment. Reductions in tidal volumes during compres- 
sion should be expected and compensated for 
appropriately. Hyperbaric mechanical ventilators 
are particularly limited in delivering high minute 
ventilations (> 15 L/min at chamber pressures > 
2.0 atmospheres absolute). If a patient's minute 
ventilation is inadequate, hypercarbia and acidemia 
may result. O2 toxicity due to HBO^ is also wors- 
ened by hypercarbia (hypercarbia causes cerebral 
vasodilation and increased cerebral blood tlow). so 
careful control of mechanical ventilation during 
HBO; is important.-^ The risk of central nervous 
system (CNS) O; toxicity is increased by hyper- 
carbia during HBO; breathing due to increased O; 
delivery to the brain.-'' 

Training of Personnel in HBO; 

Training of personnel in hyperbaric medicine is 
accomplished by several pathways. The military 
has trained physicians, nurses, and technicians in 
operation of diving and medical hyperbaric treat- 
ment facilities for many years. The U.S. Navy 
trains physicians biannually in diving medicine and 
multiplace-chamber operation. The U.S. Air Force 
trains physicians in clinical hyperbaric medicine 
through structured fellowship programs. Civilian 
physician fellowship programs are occasionally 
available at several active hyperbaric centers. Infor- 
mation regarding fellowships may be obtained 
from the Undersea and H) perbaric Medical Society 
(UHMS) in Baltimore, Maryland. Several I- or 2- 
week training courses are offered at established 
civilian hyperbaric centers. A listing of such 
courses is available from the UHMS. The National 
Oceanic and Atmospheric Administration (informa- 
tion available through the UHMS) offers a 2-week 
training course for physicians in the operation of 
multiplace chambers and the care of patients suf- 

fering from diving accidents. Some hyperbaric cen- 
ters have a small cadre of staff who ha\e thorough 
training, either from fellowships or military pro- 
grams, who subsequently train their in-house cov- 

In June 1991. the first certifying examination in 
diving and hyperbaric medical terminology was 
given by the National Board of Di\ing and Hyper- 
baric Medical Technology (New Orleans. Loui- 
siana). Passing this examination certifies thai the 
candidate has a core of fundamental knowledge in 
hyperbaric medicine. The examination may be 
taken by technicians, therapists, nurses, paramed- 
ics, and physicians. In addition, the UHMS can 
provide information about conferences and meet- 
ings regarding hyperbaric medicine. The UHMS 
publishes a newsletter. Pressure, as well as two 
medical journals. Undersea Biomedical Research, 
and Journal of Hyperbaric Medicine. The Di\ers 
Alert Network (DAN) (Duke University) also 
offers training courses for individuals interested in 
diving medicine. 

Stafring the Hyperbaric Unit 

Many hyperbaric units are not consistently busy 
enough to have a dedicated therapist or nursing 
staff Therefore, these units cross-train interested 
individuals who work in various areas in the hos- 
pital. For example, the hyperbaric unit may have 
several critical care nurses or respiratory therapists 
who normally are assigned to one of the hospital's 
critical care areas and work there except when 
called upon by the h\pcrbaric unit. Many hyper- 
baric centers select personnel from the critical care 
environment to train in hyperbaric medicine, which 
is sensible because many of the disorders for v\ hich 
HBO; is helpful occur in critically ill patients. 

Hyperbaric Physics & Terminology 

Caregivers who deal with hyperbaric medicine 
need to be well acquainted with the physics of 
gases and hyperbaric terminology. Boyle's Law 
states that the volume of a closed, gas-tilled space 
is inversely proportional to the absolute pressure 
around the space (pressure x volume = a constant). 
A common example of Boyle's Law in hyperbaric 
practice is that the patient's tympanic membrane is 




pushed inward during Lonipression. This may 
result in ear pain or drum rupture if the patient does 
not perform maneuxeis to ec|uaii/e middle-ear pres- 

Henry's Law states that the anu)unt of gas dis- 
solved in a liquid is proportional to the absolute 
pressure applied to the liquid. The body behaves 
like a liquid, dissohing considerable amounts of O; 
in biood""''^*' and tissues-^ during HBO2. 

Pressure may be expressed in several different 
units. For example. 1 atmosphere absolute (atm 
abs, or ATA) is the atmospheric pressure at sea 
level, which can also be expressed as 760 torr or 
101.32 kPa and in other ways (Table 2). Typical 
chamber pressures are 2 to 3 atm abs. I prefer to 
use atm abs as the unit of pressure measure because 
gauge pressure does not take into account the ambi- 
ent reduced barometric pressure (eg, when a cham- 
ber is operated at an ele\ated altitude). Typical 
treatment durations are 90 to 120 minutes. Some 
treatments, specifically for decompression sickness 
and arterial gas embolism, may require 4 to 6 hours 
of chamber treatment. Patients with severe decom- 
pression sickness or arterial gas embolism may 
require a treatment table (protocol) that is approx- 
imately 36 hours long."'' 

exhibit at chamber pressures.-''"' Blood gases are 
measured in ctimpressed patients by blood gas 
instruments calibrated inside the multiplace cham- 
ber.-'-*' One blood gas instrument (ABL 330. Radi- 
ometer. Copenhagen. Denmark) is able to accu- 
rately measure O2 tension of blood tonometered 
under hyperbaric conditions. Accurate measure- 
ment requires careful techniciue and rapid analy- 
sis. "" Concomitant with the increased PaO: is 
increased tissue O2 tension, which during HBO; is 
200 to 500 torr.-** 

Table 3. Pliysiologic Effects of HBO; 

Hyperoxygenation of hlood and tissue 

Vasoconstriction — reduction of: 

Compartment pressures 
02-diffusion distances 

Enhanced host immune function 
Leukocytes require O; 
Inactivation of clostridial toxins 

Mass action of gases (Henry's Law) 

Bubble reduction (Boyle's Law) 


Collagen production is 0:-dependent 
Particularly helpful in radiation-damaged tissue 

Table 2. Pressure Conversions 

1 atmosphere (atm abs)* = 1.013247 bar 
= 101.3247 kilopascal(kPa)t 
= 14.6939 psi 
= 760 ton- 
= 33.08 feet of sea water (fsw) 

* Atmosphere absolute (atm abs or ATA or atm abs) = the absolute 

pressure compared to zero pressure or an absolute vacuum. 
t 1 pascal = 1 new ton x meter.-" 

Physiologic Effects of HBO. 

HBOi causes many physiologic effects that are 
clinically important (Table 3). HBO; produces sub- 
stantial increases in arterial O; tension (Henry's 
Law). At typical treatment pressures, individuals 
with normal pulmonary function have arterial 
blood partial pressures (PaO:) of 1.500 to 2.000 
torr.-^-^ Patients with abnormal pulmonary func- 
tion may require higher pressures to achieve the 
equivalent PaO: that patients with normal lungs 

Optimal host defense requires adequate poly- 
motphonuclear (PMN) leukocyte function. PMN 
leukocytes depend on O; for rapid and efficient 
killing of engulfed microbes.'- HBOt is used to 
raise tissue Po:- improving host defense in severe 
infections, particularly in immunocompromised 
patients. HBO. is used for treatment of gas gan- 
grene because high tissue O. tensions inactivate 
clostridial toxins" and kill most clostridial spe- 

Recompression causes the volume of intra- 
vascular and tissue bubbles (in arterial gas embo- 
lism and decompression sickness) to become 
smaller (Boyle's Law). This minimizes micro- 
vascular occlusion and tissue distention in those 
clinical conditions. '^ 

By a mechanism that is unknown, HBO; causes 
vasoconstriction.'*''^ Even though vascular beds are 
vasoconstricted during HBO; treatment, O; deliv- 
ery is not reduced, because of the amount of O; dis- 
solved in the plasma.-''-*'"^ Vasoconstriction is use- 
ful in reducing edema in burns'** and post-ischemic 




States,'' and in lowering intracumpartmental pres- 
sures in acute crush injury.""' 

Patients with poorly healing wounds may be 
treated with HBO^ to stimulate fibroblast prolif- 
eration^' and to enhance collagen production, an 
Oi-dependent process.'*- This effect is especially 
important in patients who have ischemic tissues 
due to radiation therapy. HBO^ has been shown to 
stimulate angiogenesis into previously irradiated 
tissue""" Controlled trials in human patients with 
osteoradionecrosis of the mandible ha\e demon- 
strated impro\ed outcome with a combined 
approach using HBO; and surgery, compared to 
surgery alone."''^ ""^ 

Other properties of HBO; include enhanced 
effectiveness of aminoglycoside antimicrobials"* 
and possibly improving red blood cells" deform- 

Emergency Uses of Hyperbaric O^ (Table 1 ) 

.\rterial Gas Embolism (AGE) 

AGE occurs in divers'*'^ and may complicate 
medical procedures.'^"""'' In diving, AGE occurs dur- 
ing ascent (pressure reduction) when gas expansion 
exceeds the rate of gas elimination through the air- 
ways. The expanding gas disrupts alveoli and 
enters the pulmonarv' capillary circulation. From 
there, the gas reaches the left heart and commonly 
embolizes the vasculature of the brain"*" and occa- 
sionally the coronary arteries."^"* AGE symptoms 
generally are acute and dramatic in onset.'*'' They 
may include loss of consciousness, hemiplegia, 
abnormal mentation, and/or seizures.*'' Any diver 
who develops neurologic symptoms, including an 
abnormal mental status, within minutes following a 
compressed-air SCUBA di\e should be considered 
as possibly having an AGE. Prompt referral to a 
recompression facility and evaluation by phy-- 
sicians trained in hyperbaric medicine are impor- 
tant. The U.S. Navy suhmarnie escape training evo- 
lutions (free water rapid ascents from at least >() 
fsw) have demonstrated that immediate recompres- 
sion and treatment with HBOi ha\e dramatic, 
favorable results.'''" Numerous reports of .AGE 
treated successfully with HBO; confirm its effi- 
cacy,'*'''""^'' although there has ne\er been a pros- 
pective randomized clinical trial (PRCT) com- 
paring HBO; to any other form of therapy for 

AGE." Several studies suggest that even delayed 
treatment of AGE with HBO; improves out- 



Decompression Sickness 

Sport SCUBA diving accounts for approx- 
imately 500 reported cases of "the bends."" or 
decompression sickness (DCS), per year in the 
USA.*" DCS has also been described in aviators 
subjected to a reduced ambient pressure.''' In div- 
ers. DCS results when an indiv idual breathing com- 
pressed air at increased ambient pressure returns to 
a lower pressure too rapidly.'-^ For example, if a 
diver is exposed to increased ambient pressure and 
is breathing air (799( nitrogen — N;) the partial 
pressure of N; increases in proportion to the diver's 
depth, and the amount of N; dissolved in tissue 
increases (Henry"s Law). As the diver ascends, the 
ambient pressure decreases. The reduced pressure 
causes the N; to move from tissues to the blood and 
to be eliminated by the lungs ("off-gassing"). If off- 
gassing of N; occurs too rapidly, bubbles may 
form. Bubbles can develop in tissue such as bone, 
cartilage, nerves, and blood. '"^ Generally, patients 
with DCS describe pain and frequently ha\e an 
abnormal neurologic examination.'-^''" A life-threat- 
ening though rare fomi of DCS is the chokes, 
caused by bubbles forming in the pulmonary inter- 
stitium and in \enous blood. Gas in the pulmonary 
interstitium impairs \entilatory gas exchange, and 
bubbles in venous blood congest the pulmonary cir- 

The combination of recompression and HBO; is 
the mainstay of treatment for DCS.'^ Recompres- 
sion of the patient with DCS mechanically com- 
presses bubbles to alleviate microvascular obstruc- 
tion. High concentrations of inspired O; produce a 
gradient for N; transport out of the bubble''- and 
also oxygenate ischemic tissues. It has recently 
been recognized that complement activation by 
intravascular bubbles contributes to the manifesta- 
tions of DCS."" 

Prompt clinical response is often seen in patients 
with DCS when treated with HBO;. The Divers 
Alert Network data reveal that approximately one 
third of all cases of DCS had residual sv mptoms 
after HBO; had been discontinued."" hut this num- 
ber may be infiuenced by many patients who pre- 


RE.SPIRA'rQRY CARE • JULY "92 Vol 37 No 7 


sented days after the dc\eliipnicnt of symptoms. 
Most patients impro\e. ho\\e\er. o\cr the ensuing 
few weeks or months. HBO; treatment of patients 
with DCS is also important to prevent d>sbaric 
osteonecrosis, which is a complication of inad- 
equate treatment of DCS.*^ Any di\er who man- 
ifests pain or neurologic symptoms v\ithin minutes 
or up to several days after a compressed-air di\e 
should be considered as possibly experiencing 

Carbon Monoxide Poisoning 

Carbon monoxide (CO) poisoning is the most 
common poisoning seen in the United States, 
accounting for 56.133 deaths from 1979 through 
1988.^^ Of these. 25.889 were suicides. 210 were 
known homicides. 15.523 were associated with 
severe burns or house fires, and 1 1,547 were unin- 
tentional. Any flame source (including propane- 
powered forklifts, gasoline engines, fires, and heat- 
ing units with inadequate ventilation) produces CO 
as a by-product of combustion. CO poisoning also 
results from exposure to methylene chloride.^^ 

CO binds to hemoglobin (Hb). forming carboxy- 
hemoglobin (COHb)." "' Furthermore, the COHb 
causes the oxyhemoglobin-dissociation curve to 
shift to the left, which reduces O2 transport at the 
cellular level. ^'' The major pathophysiology of CO 
seems to be the anoxia that results from the inabil- 
ity of Hb to carry O..™ 

HBO2 traditionally has been used in CO poi- 
soning to accelerate the elimination of CO.^' ^' Evi- 
dence suggests that HBO2 improves the outcome in 
CO poisoning even if the COHb level has returned 
to normal by the time of treatment. "" Possible 
explanations for this observation '" include the 
hypothesis that CO not only binds to Hb but also 
binds to cytochromes'^^^ and to other enzyme sys- 
tems that are important for intracellular O: utiliza- 
tion.'"*''^ Studies in animals have demonstrated that 
CO poisoning produces lipid peroxidation in tlie 
brains of the poisoned rats.**'^ In this animal model. 
HBO2 prevents lipid peroxidation, whereas nor- 
mobaric O2 (100% O2 at sea-level pressure) does 

Two PRCTs have been reported regarding HBO2 
and acute CO poisoning. ^-^' Raphael et al in 
France randomized 343 acutely poisoned patients 

who liad ne\er lost consciousness to receive either 
normobaric O2 or HB02.^" The patients received 
either 6 hours of normobaric O2 or one HBO2 treat- 
ment (30 minutes compression. 2 atm abs x 60 
minutes. 30 minutes decompression) plus 4 hours 
of normobaric O2. At 1 -month follow-up there was 
no difference in outcome between the two groups. 
Raphael et al concluded that HBO2 is not necessary 
in acute CO poisoning if the patient never lost con- 
sciousness. In another French study. Ducasse et al 
randomized 27 patients to receive normobaric Oi 
or HB02.^' They demonstrated that all patients 
with moderate CO poisoning treated with HBOi 
had impro\ed cerebral blood flow and normalized 
their quantitative electroencephalograms at 3 weeks 
when compared to the normobaric 02-treated con- 
trols. They recommended all patients with CO poi- 
soning be treated with HBO2. 

Raphael et al's study^" can be criticized because 
it is possible that the dose of HBO2 was inadequate 
compared to higher pressures and longer durations 
of HBO2 used in the USA. Furthermore. 10.5'7f of 
their patients were lost to follow-up. and their out- 
come assessment did not include fonnal tests of 
higher cortical function, which are sensitive indi- 
cators of impairment in CO poisoning.'*''"* Ducasse 
et al's study'*-' can be criticized because it is dif- 
ficult to know the pertinence of quantitative EEGs 
and measures of cerebral blood flow in CO poi- 
soning. No other outcome \ariables were studied 
by Ducasse et al beyond a subjective questionnaire, 
which ma\' be too insensitive a measure to assess 

Goulon et al retrospectively demonstrated a 
reduced mortality in acute CO poisoning if HBOt 
was used within 6 hours after exposure.**"^ 

It is unclear precisely what role HBO2 has in the 
treatment of acute CO poisoning. Legally, the stan- 
dard of care for acute CO poisoning is \007c normo- 
baric O2.'**' A survey of the beha\ior of academic phy- 
sicians regarding referral of CO-poisoned patients to 
HBO2 units also supports this position.*' Many phy- 
sicians in the hyperbaric community believe that 
there is ample evidence to support the administration 
of HBO2 in acute CO poisoning. '■*-'"*■'•*** Some 
non-HB02 physicians have argued that a PRCT is 
needed to prove the efficacy of HBO: in acute CO 
poisoning.^''''" However, members of the hyper- 
baric community feel strongly that a prospective 




trial is not indicated in CO poisoning, arguing that 
a PRCT would be unethical.^'*'" It seems to me that 
HBO2 could be compared with normobaric O; 
treatment in a well-designed PRCT. Pending a 
prospective trial from the USA that adequately 
addresses the concerns from the French prospective 
trials, the criteria that seem reasonable to refer 
patients with CO poisoning to HBO2 centers are 
summarized in Table 4.** -'-■-''*■''- 

Table 4. Criteria for HBO; in Acute CO Poisoning* 

History of unconsciousness 

Abnormal end-organ function (abnormal psychometric test or 

any manifestation of cardiac or other tissue ischemia) 
Metabolic acidosis 
Carboxyhemoglobin > 25% 
Concurrent pregnancy 

*From References 8:33-59 and 92. 

Gas Gangrene and Necrotizing 
Soft-Tissue Infections 

Gas gangrene is caused by clostridial bacteria.'^ 
The hallmark of the infection is myonecrosis due to 
toxins released by the bacteria.'''* Gas gangrene can 
occur after trivial injury and may be rapidly fatal 
without early recognition and aggressive man- 
agement. Management includes wide surgical 
debridement and high-dose antimicrobials.''^ The 
antimicrobial of choice has been high-dose pen- 
icillin.'''^ although primaxin appeared to have 
enhanced effectiveness against Clostridia when 
compared to penicillin in animal studies.'"' Adjunc- 
ti\e HBO2 was originally used by Boerema and his 
associates in the early 196()s. the reasoning being 
that high O; tensions would be bactericidal to clos- 
tridial organisms.' Indeed. HBO, inacti\ales clos- 
tridial toxins^^'' and inhibits clostridial replication.'''' 
In animal experiments, HBO, has been clearly 
demonstrated to reduce morbidity and mortality.'' 
In two retrospective clinical trials. HBO^ reduced 
hoih morbidity and niorlalitv when utilized 

Necrotizing soft-tissue infections seem to be 
occurring at an increased frequency, with approx- 
imately 1,000 cases per year reported in the 
USA.'"" Necrotizing fascitis can occur in a normal 
host but is more common and severe in diabetic 

and immunocompromised patients."" The main 
effect of HBO2 in these infections is to raise tissue 
O2 tension, enhancing leukocyte function.^-'"-'"-' 
Polymorphonuclear leukocyte function is dras- 
tically impaired in hypoxic tissue.'"'' Furthermore, 
anaerobic bacteria replicate rapidly in low O; ten- 
sion environments.'"'' HBO2 can limit anaerobic 
replication by increasing tissue O2 levels. A recent 
retrospective analysis compared HBO: ^^'th "'^ 
HBO2 as an adjunct to surgery and antimicrobial 
therapy in patients with necrotizing fascitis.'"" A 
significant decrease in mortality and a reduced 
number of surgeries treated w ith HBO^ were demon- 
strated. A 1988 review of 272 patients with necro- 
tizing soft-tissue infections showed an overall mor- 
tality of 38.5% in patients who were treated with 
surgery and antimicrobial therapy but did not 
receive HBO2,'"' whereas HBO2 reports of recent 
date demonstrate a mortality of 207r. '"*'"*■ '"^ There 
has been no PRCT comparing HBO^ to no HBO2 in 
the treatment of necrotizing soft-tissue infections. 

The most important treatment in necrotizing 
.soft-tissue fascitis is to recogni/c the disease 
promptly and perform wide surgical debridement. 
If aggressive surgery is not performed initially, 
patients" outcomes can be expected to be 
worse. '"^■'"'^ Broad-spectrum antimicrobials are the 
.second treatment of choice, and HBO; is the third. 
HBO; is expensive and is not necessary in all 
patients with necrotizing soft-tissue infections. 
HBO; should be considered in patients with these 
infections who arc at high risk for complications 
and/or death (eg, immunocompromised hosts or 
patients failing standard therapy).'"" For best out- 
come, however. HBO; should be initiated soon 
after recognition of ihe infection.'"''-'''^ 

Acute Traumatic Ischemia/Crush Injury 

HBO; is indicated in acute crush and traumatic 
ischemia when there is ongoing tissue necrosis and 
ischemia from impairment of micro\ascular cir- 
culation. HBO; increases tissue O; levels"' and 
increases O; dissolved in plasma severalfold.-'^"* 
Another favorable effect of HBO; in crush injuries 
is vasoconsiriction,'^-" which may reduce intra- 
compartmental pressures.'"'"^'"'" HBO; maintains 
tissue O; delivery in the face of vasoconstriction.-' 
In animal models of compartment syndrome, 


Rl-SI'IRATOR^' CARH • JULY "92 Vol .^7 No 7 


Strauss et al have shown that HBO; ameliorates the 
injury.""'" NeniirotT has demonstrated that HBO, 
can salvage axial flaps, especially when used in 
combination with pentoxitVliine, a red cell- 
deforming agent."- Nylander et al demonstrated a 
significant reduction in edema following acute 
ischemia in animals treated with HBO^.^^ We have 
been using a combination of pentoxifylline and 
HBO2 for most acute traumatic ischemic injuries, 
with favorable clinical results. There have been no 
PRCTs for crush injury and acute traumatic ische- 
mia. I think this would be particularly difficult 
because these represent a heterogenous group of 
disorders. Such a trial would require that a large 
number of patients in the non-HBO; and HBO; 
groups be compared statistically. However, animal 
experiments have demonstrated the efficacy of 
HBO-> in acute traumatic ischemia and crush 
injury.-^" ^"""-"^ 

Compromised Grafts and Flaps 

The HBO; properties of hyperoxygenation and 
edema reduction outlined in the discussion of acute 
traumatic ischemia are applicable to compromised 
grafts and flaps. HBO; is used in compromised 
grafts and tlaps to improve microvascular O; deliv- 
ery.-^ Extensive animal data"" "^ and human 
data"''-" show enhanced survival of compromised 
skin grafts with the use of HBO;. Pedicle flaps in 
rats have a significantly improved survival when 
HBO; and pentoxifylline are used in combination, 
as compared to controls, HBO;, or pentoxifylline 
alone."- Any patient with a compromised, poten- 
tially viable ischemic graft or flap should be con- 
sidered for immediate HBO;. Another important 
property of HBO; in the treatment of grafts and 
flaps is to stimulate neovascularization into prob- 
lem wounds, which is important for survival of a 
compromised graft."""''' 

middle ear. Pain and possible tympanic rupture will 
occur if the patient cannot force air through the 
Eustachian tube into ilic middle-ear space. Most 
conscious, cooperative patients learn maneuvers to 
equalize middle-ear pressure. If the patient is 
unable to perform these maneuvers satisfactorily 
and requires HBO;, then tympanotomy tubes may 
need to be inserted. It has been my practice to per- 
form emergency myringotomies or to have tympan- 
otomy tubes placed in intubated patients who 
require HBO;. Without tympanic-membrane vent- 
ing, an intubated patient may or may not equalize 
middle-ear pressure during chamber pressurization. 
If the middle-ear space does not adequately equal- 
ize pressure, irreversible damage to the inner ear 
and/or the ossicles might occur during compres- 
sion. In my opinion, the risk-benefit ratio favors 
performing bilateral myringotomies in intubated 
patients. There are no prospective data, however, 
showing that myringotomies are important in intu- 
bated patients requiring HBO;. 

Anxiety in patients receiving HBO; is something 
that all hyperbaric centers must deal with occa- 
sionally. Some patients refuse to undergo HBO2 
because of claustrophobia. In my experience, this is 
rare. Many patients may express anxiety about 
HBO;, but when they understand its role and why it 
is important to enhance the outcome in their par- 
ticular disease, they will accept the therapy. 

It is important to recognize that the patient 
should have control of his treatment. If a patient 
requests to be let out of the chamber, then we 
decompress the patient. It is important that the 
hyperbaric staff interact with the patient, frequently 
informing him what the therapy is and why it is 
being used in his particular Distraction of the 
patient during treatment minimizes anxiety: this 
can be done through con\ersation or having the 
patient watch television or a movie.'-' Anxiolytics 
such as diazepam are sometimes helpful. 

Patient Problems Associated with HBOt 

Risks of HBO, 

The most common patient-related issue in HBO; 
is equalization of middle-ear pressure. The middle- 
ear space is a potentially closed space. During com- 
pression in a hyperbaric chamber, the tympanic 
membrane is pushed inward because there is more 
pressure in the auditory canal than there is in the 

It is well recognized that O; can produce pul- 
monary pathology'-- and in the hyperbaric range 
can cause O; toxicity to the CNS, generally man- 
ifested by seizures.'""--" The incidence of sei- 
zures in the hyperbaric population is less than 1 in 
5,000 treatments,'-'-'-'' and seizures are reversible if 




recognized promptly. Pulmonary O2 toxicity is gen- 
erally not a problem because exposures are limited 
in duration and frequency to prevent such toxicity. 
Having the patient breathe air intermittently (air 
breaks) during HBO. les.sens the risk ot'CNS'-' and 
pulmonary'-" O. toxicity.'" Some HBO. units rou- 
tinely provide air breaks, but many do not. Cer- 
tainly, air breaks extend the amount of time that a 
patient can safely breathe HBO;.'-'' 

Re\ersible visual changes have been described 
in patients receiving chronic HBO..** '■"'•'-"*'-'•'-*' It 
generally takes more than 20 daily treatments to 
demonstrate these reversible visual changes. The 
lens of the eye appears to be altered by HBO^.'"^ 
Once the course of HBO2 ceases, the visual 
changes generally gradually return to their pre- 
HBO: baseline.** '^"■'--"-^'-' Cataracts can be 
induced by prolonged daily HBO; (> 150 daily 
HBO; exposures).'-"^ but in the USA this problem is 
rarely encountered because the course of HBO; is 
generally limited to < 60 treatments.' 

Septic patients, such as those with necrotizing 
soft-tissue infection or gas gangrene, may have 
unexpected cardiovascular changes during HBO;.'- 
Patients receiving pressors (eg, dopamine or dobu- 
tamine) require careful monitoring and astute titra- 
tion of these drugs during HBO;.'' 

Chamber and Equipment Operation 

Communication is enhanced by ha\ing trained 
hyperbaric nurses, therapists, or technicians inside 
a multiplace chamber with the patient or by having 
the attendant outside the chamber be directly vis- 
ible to the patient in the monoplace chamber. Voice 
communication is easily accomplished in the mon- 
oplace chamber by an intercom. Certainly, observa- 
tion is an important element for any patient receiv- 
ing HBO;: simple observation may discover clues 
that a patient is ha\ ing early manifestations of O; 

It is important that critically ill patients be ade- 
quately monitored during HBO;. Electrocar- 
diographic tracings are easily performed during 
HBO;.'" Blood pressure may be monitored continu- 
ously if the patient has an arterial catheter.'-'^" or it 
may be monitored noninvasively.'^'"- Intravenous 
(I.V.) fluids can be administered to patients in the 
multiplace chamber by placing the I.V. pump 

inside the chamber.'^' In the monoplace chamber. 
I.V. fluids are administered by a high-pressure 
pump located outside the chamber. \ ia tubing that 
enters the chamber through specially designed 
pass-throughs.'- As previously mentioned, atten- 
tion to detail is particularly important \\ ith mechan- 
ical ventilation of patients during HBO;.-'" Recent 
reviews of critical care in both the monoplace 
chamber'- and the multiplace chamber"' are avail- 
able, showing that critically ill patients can be ade- 
quately cared for in both types of facilities. 

Outcome Studies in HBO; Therapy 

In much of clinical practice, there are limited 
PRCTs for efficacy; HBO; therapy is no exception. 
The diseases that have been presented in this dis- 
cussion have been approved for HBO; treatment by 
the Scientific Committee of the Undersea and 
Hyperbaric Medical Society (UHMS).' This com- 
mittee is composed of members of the hyperbaric 
community who have thorough knowledge of 
HBO;. Only after careful review of the pertinent 
literature and the achievement of expert consensus 
are disorders approved to receive HBO;. Many 
third-party payers consider the UHMS guidelines 
to be acceptable for reimbursement.- Table 5 sum- 
marizes outcome studies for each of the curtent 
UHMS-appro\ed indications for HBO; therapy."^ '^' 
Certainly, PRCTs are lacking for most of the indi- 
cations for HBO;, but animal data and anecdotal 
human data are available to support all of them. 
Pending outcomes from PRCTs for HBO;, the 
UHMS guidelines are useful criteria to follow 
regarding referral and treatment. In m\ opinion, to 
treat patients without one of the indications listed 
in Table 1 requires an investigational protocol. 

The Role of Respiratory Care Practitioners in 
HBO, and Future Directions of HBO; 

Respiratory care practitioners (RCPs) operate 
chambers at many HBO; centers in the United 
States. Even if the Respiratory Care Department 
does not manage the HBO; unit, the skills of the 
RCPs are generally needed to assist with critically 
ill patients requiring mechanical ventilation during 
HBO; therapy. 




Table 5. Summary ot Data Supporting Use of HBO; 


References Showing that HBOi Is Useful 



Prospective, Randomized 
Clinical Trials/Results 

Arterial gas embolism/ 
decompression sickness 

CO poisoning 

Gas gangrene 
Necrotizing fascitis 
Traumatic ischemia 
Diabetic wounds 
Radiation necrosis 
Exceptional anemia 




102, 105 

no. Ill 




5. !44. 145 

1(5-14), 49-52, 



100, 106, 107 
109, 119 
117, 118, 120 
42, 134-136 
140, 141 

44,46, 142, 143 
146, 147 

No trial performed 

HBO, useful"/ 
not useful*- 

No trial performed 
No trial performed 
No trial performed 
No trial performed 
No trial performed* 
No trial performed 
HBO; useful^- 
No trial performed 

*Baroni et al demonstrated that HBO; is useful in diabetic patients uith fool infections, but the trial, though prospecti\e. was not randomized. 

At LDS Hospital in Salt Lake City, an RN clin- 
ical coordinator assists the HBO; physician with 
the initial evaluation of the hyperbaric patient. 
RCPs are responsible for orienting the patient to 
the HBO: unit, discussing with the patient the sen- 
sations associated with HBO;, and establishing a 
schedule for the patient. In addition. RCPs treat 
patients in the chamber and direct many aspects of 
patient care during HBO; therapy. For critically ill 
patients, a critical care nurse, while often not phys- 
ically present, is available if this is clinically 
required. The HBO, unit at LDS Hospital is adja- 
cent to the Shock-Trauma-Respiratory Care Unit, 
so nurses are readily available. 

Mechanical ventilators for critically ill patients 
must be carefully monitored during HBO; ther- 
apy.'--'-- RCPs possessing a comprehensive 
knowledge of respirator}' therapy, gas laws, and 
hyperbaric physiology — including the risks of 
HBO; — are important for the care of the critically 
ill, mechanically ventilated HBO; patient. 

It is, unfortunately, a common scenario that 
patients are referred to the HBO; unit as a last-ditch 
effort when all other treatment options have failed. 
When HBO; does not effect the desired outcome, 
the referring physician is likely to be less 
impressed with the results of HBO;. It would be 

optimal if patients could be considered for hyper- 
baric referral earlier in their disease process. This 
can come only through education. Even if the HBO 
unit is some distance away, it would be reasonable 
for the patient's caregivers to communicate with 
the HBO; unit consultant. This does not necessarily 
result in a patient transport, but rather establishes a 
dialogue between the hyperbaric consultant and the 
patient's physician that can expedite the referral 
process if it becomes necessary. 

I find that physicians who are unfamiliar with 
hyperbaric therapy generally do not think about it 
or are unaware of its role. Often they are negative 
toward hyperbaric therapy, but after discussing its 
effects, they seem more interested in possible 
patient referral. The respiratory therapist can be a 
useful liaison between the hyperbaric center and 
the practising non-hyperbaric physician. Some- 
times if a knowledgeable therapist only mentions 
that HBO; may be a useful adjunct, this may 
prompt a physician to seek the HBO; consultation, 
even if that hospital does not offer HBO;. 

Since the occasion of the conference at which 
this paper was given, the National Heart, Lung, and 
Blood Institute, of the National Institutes of Health, 
has published a workshop report regarding HBO; 
therapy. '"""^ The consensus of the workshop under- 




scores the lack of understanding of the basic patho- 
physiology of oxygen toxicity, bubble formation in 
DCS. effects of bubbles at the microvascular level, 
CO poisoning, mechanisms of wound healing, and 
the effect that oxygen might have in fighting infec- 
tious diseases. The effects of HBOi on these dis- 
eases are not clearly known, especially at the 
molecular and subcellular levels. Research into 
these areas is needed and important. Clinical- 
outcome studies to evaluate the role of HBO; in the 
diseases presented herein are encouraged by the 
workshop — a conclusion that 1 ha\e attempted to 
echo in this paper. 

Continued growth of clinical hyperbaric med- 
icine in the United States can be expected. HBO; is 
highly cost-effective for some disease pro-'**''*'' As medical economics become more 
constrained, it is imperative that the HBO; com- 
munity demonstrate the efficacy of this therapy 
with well-designed prospective clinical trials. Res- 
piratory care can play an important role by aiding 
with clinical trials and by enhancing the awareness 
of other medical practitioners of the indications for 



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Weaver Discussion 

NemirofT: One risk that I didn't see 
in your list has occurred in our series 
of hyperbaric therapies, and that is 
treating a malignant tumor of 
unknown potential. A significant 
body of literature suggests that 

hyperbaiic oxygen can accelerate 
tumor growth at least during the 
tumor's proliferative phase.'- In our 
series, we did not know of the pres- 
ence of a tumor, and in one case 
there was a necrotizing laryngectotiiy 
site and in a second patient a squa- 
mous cell carcinotna of the tonsue. 

These were chronic treatments, mul- 
tiple treatments, and, in both cases, 
patients had spectacular carcino- 
matosis. If we retreat to the labor- 
atory and animal and tissue culture 
work, we find that certain tumors 
w ill accelerate or decelerate depend- 
ing on the hyperbaric ox\gen. in 




controlled double-blind studies.' I 
just v\ant to add that Ie\el of caution, 
that hyperbaric oxygen in certain sit- 
uations can be carcinogenic. 

1. Cerutti PA. Prooxidant states and 
tumor promotion. Science 1985: 227 

2. McMillan T, Calhoun KH. Mader JT, 
Stiernberg CM. Rajaraiiian S. The 
effect of hyperbaric oxygen therapy 
of oral mucosal carcinoma. Laryngo- 
scope 1989;99(3):24l-244. 

3. Wheeler RH. Dirks JW, Lunardi 1. 
Nemiroff MJ. Effect of hyperbaric 
oxygen on the cytotoxicity of adri- 
aniycin and nitrogen mustard in cul- 
tured Burkitt's lymphoma cells. Can- 
cer Res 1979:39:370-375. 

Weaver: That point was discussed at 
the Problem Wound meeting, pri- 
marily by PM Nemiroff. Nemiroff 
looked at tumors in mice and dem- 
onstrated that tumor growth was not 
enhanced with hyperbaric oxygen.' 
Marx and Johnson demonstrated a 
significantly reduced cancer rate in 
patients previously irradiated who 
had received hyperbaric oxygen ther- 
apy (as part of a protocol for facial 
reconstruction) than in similar pa- 
tients who had not been treated with 
hyperbaric oxygen.- McMillan and 
co-workers showed that hyperbaric 
oxygen inhibited carcinogenesis in 
animals exposed to a mucosal car- 
cinogen. They did, however, find 
that hyperbaric oxygen enhanced 
pre-existing tumor growth.' Using a 
similar animal model, Marx and 
Johnson did not observe tumor 
growth enhancement with hyperbaric 
oxygen.- That's certainly been a con- 
cern of a lot of people. If you look at 
patients with head andVor neck can- 
cers, the baseline rate of either a new 
primary or recrudescence of the old 
one is around 10%. So, it's some- 
times very difficult for me to say 
whether their cancer is now caused 
by hyperbaric oxygen or it's a coin- 
cidence. The animal studies would 
certainly tell us that it's coincidental 

and not related to hyperbaric oxygen. 
I don't know of a lot of human data, 
but there was consensus at the Prob- 
lem Wound meeting last year and 3 
years ago that no longer is hyper- 
baric treatment felt to be a cause of 
accelerated tumor growth. 

1. Nemiroff PM. Effects of hyperbaric 
oxygen on growth and metastases of 
the Lewis lung tumor in mice. J 
Hyperbaric Med l988:3(2):89-95. 

2. Marx RE. Johnson RP. Problem 
wounds in oral and maxillofacial sur- 
gery: the role of hyperbaric oxygen. 
In: Davis JC, Hunt TK, eds. Problem 
wounds: the role of oxygen. New 
York: Elsevier, 1987:107-109. 

3. McMillan T, Calhoun KH, Mader JT, 
Stiernberg CM, Rajaraman S. The 
effect of hyperbaric oxygen therapy 
on oral mucosal carcinoma. Laryngo- 
scope 1989,99:241-244. 

Nemiroff: I don't believe the blanket 
statement can be made. It depends on 
the tumor type and maybe a subtype 
of that particular tumor. The tissue 
culture that I studied was Burkitt's 
lymphoma' because it's an easily 
culturable malignancy. In that case, 
we could accelerate, decelerate, 
increase cell growth, and increase 
cell death with hyperbaric chemo- 
therapy. But, again, the results are 
very tumor specific. 

I. Wheeler RH. Dirks JW. Lunardi L 
Nemiroff MJ. Effect of hyperbaric 
oxygen on the cytotoxicity of adri- 
amycin and nitrogen mustard in cul- 
tured Burkitt's lymphoma cells. Can- 
cer Res 1979;39:370-375. 

Weaver: OK. Thank you. 
Porter: Because you have the avail- 
ability of hemodynamic monitoring 
in your chamber, and you've seen 
this questionable worsening of heart 
failure, have you noticed any pul- 
monary artery (PA) pressure changes 
or pulmonary capillary wedge pres- 
sure changes to suggest that left ven- 
tricular (LV) function gets worse in 

this setting, or have you looked into 

Weaver: That's a good question. 
Well, we have looked into it in septic 
patients. I presented an abstract a 
year ago;' in that work, we had 4 
septic patients with pulmonary arte- 
rial hemodynamic monitoring. Vir- 
tually no change occurred in any var- 
iable when we put all of their data 
together. In normal individuals, 
there's good data for the heart rate 
and the cardiac output being reduced, 
but in septic patients (they all were 
on controlled mechanical ventilation, 
sedated, and paralyzed), the heart 
rate virtually did not change. Blood 
pressure did not change. All of these 
patients were receiving LV. dobuta- 
mine or dopamine, and we tried to 
keep it at the same infusion rate. 
There was basically no change. Last 
year I saw 2 patients who, when 
pressurized in the chamber, dropped 
their blood pressure. When we meas- 
ured the cardiac output and measured 
the wedge pressure, the wedge didn't 
change but the cardiac output fell in 
both patients, lasting about 10 min- 
utes. Then after we reached treat- 
ment pressure, the cardiac output pla- 
teaued back to pre-hyperbaric levels. 
I think what we were seeing, actu- 
ally, was the reduction in the dop- 
amine rate. The pumps that we use 
are rather sensitive to chamber pres- 
sure, and I think sometimes we take 
for granted that they provide an ade- 
quate and an appropriate dose. Sub- 
sequently, we've looked at pump 
perfonnance, and it's highly var- 
iable. Some of them work well; some 
of them don't work well — even mod- 
els of the same line. So, in retrospect, 
I wonder now if indeed we were fail- 
ing to provide an adequate dose of 
dopamine, and that's why we were 
dealing with a reduced cardiac out- 
put and hypotension that resolved 
after a few minutes. Usually, the 
nurses will reach over and start 
increasing the dopamine rate when 
they see hypotension. For those two 




circumstances, I said, "Don't do tiiat. 
Let's see what happens to the 
patient." After we reached chamber 
pressure, things equilibrated. Their 
blood pressures came hack up. Their 
cardiac output came hack up. i"\e 
not looked at hemodynamics in 
patients with congestive heart fail- 
ure. I tend not to put man\ patients 
with congestive heart failure and 
Swan-Gan/ catheters in the chamber: 
so. I can't tell you what happens in 
that group. 

1. Weaver LK. Pulmonary artery cath- 
eter use in critically ill patients treated 
in the monoplace hyperbaric chamber 
(abstract). Undersea Biomed Res 

Fanta: What are the risk factors for 
decompression sickness and arterial 
gas embolism? Certainly from a 
physiologic point of view, as you 
mentioned, one would predict that 
maldistribution of ventilation would 
be a predisposing factor; and the 
populations at risk, I imagine, would 
include people with mucus hyper- 
secretion or bronchoconstriction. Of 
the thousands of cases a year, is there 
a disproportionate number of persons 
with excessive mucus and broncho- 
spasm, such as asthmatics or chronic 

Weaver: No, probably not, but we 
tr\ pretty vigorously to prevent peo- 
ple with airway obstruction or 
mucus-producing diseases froin div- 
ing. The consensus has been reached 
by diving physicians in several work- 
shops on fitness to dive in the last 5 
to 10 years. The consensus of diving 
medical authorities worldwide is that 
people with asthma should not 
dive — that includes people with si- 
lent asthma and a positive methacho- 
line challenge — because of the fear 
of gas trapping. Are there data? No. 
Everybody has his own anecdote. 
Sure, I've seen several cases of gas 
embolism, and I've seen .several 
cases in which it occurred in people 

with asthma, but I don't know what 
the denominator is. I don't know 
how many people with asthma or 
occult asthma are diving. The Div- 
ers" Alert Network (DAN) has tried 
III look at this. A paper was pre- 
sented in June, in which Corson et al 
.said, "It looks like people with 
asthina who dive may have a iwo- 
lold-risk incidence in developing gas 
embolism, over what seems to be the 
baseline risk."' But their data are 
really soft, and they admit that 
because we don't have a good 
denominator. But, again, the con- 
sensus is that people with airflow 
obstruction should not dive because 
of the possibility of regional gas 
trapping and arterial gas embolism. 

In terms of decompression sick- 
ness, what are the risk factors? Basi- 
cally, not following tables, diving 
too aggressively, diving many times 
each day, flying too soon after the 
dive (with a reduced cabin pressure), 
and rapid ascent rates — and, by 
rapid. I mean exceeding I foot per 
second. That's a real practice .skill. It 
takes a lot of practice to come up 
slowly, and that's where the 'safety 
stop' is probably an important ele- 
ment in reducing decompression 
sickness. Again, I don't know that 
we have any hard data about this. We 
know what happens to bubbles by 
Doppler detection, and they go away 
with safety stops and with slower 
ascent rates. But, we really don't 
know if that's going to affect the risk 
or the rate of decompression sick- 
ness. As far as the candidates — old 
divers, people, women. I'm 
not sure we can make any statements 
about that. For years we've said. 
"Obese people have an increased risk 
and older people have an increased 
risk." These statements do not seem 
to be borne out by the DAN data- 

1. Corson K.S. Dovenbarger JA. Moon 
RE. Hoddcr ,S, Bennett PB. Risk 
assessment of asthma for decom- 

pression illness (abstract). Undersea 
Bioined Res 1 99 1 : 1 7( Suppl ): 1 6- 1 7. 

Mathews: Can you possibly com- 
ment on the controversy that's going 
on regarding changing the 'fly-dive' 
or the 'dive-fly' situation? That 
seems to be a big controv ersy at least 
in the lay literature. 
Weaver: Well, the concern is that 
w iih a reduction in ambient pressure, 
bubbles may form. The most con- 
servative recommendation is that 
when you've been diving, wait 24 
hours before flying at reduced cabin 
pressure. (Of course, virtually every 
flight you take will be at reduced 
cabin pressure.) If diving requiring 
decompression stops was performed. 
48 hours' wait is recommended. 
Many members of the diving com- 
nnniity are really sort of troubled 
with that recommendation because 
they want to dive and then leave the 
next day early in the morning — that 
sort of thing. DAN recently modified 
the recommendations of the flying 
after diving workshop. DAN now 
recommends a minimum 12-hour 
surface interval. If multiple dives, 
multiple days' diving, or decom- 
pression diving was performed, an 
extended time beyond 12 hours is 
encouraged. Again, most of the data 
comes from DAN, where they're tak- 
ing calls from divers who are now 
back in the United States from diving 
at nice places like this, and are 
"bent." So, they're being very con- 
servative in their recommendation. I 
don't think that we know precisely 
when divers may ascend to altitude, 
and I think it's going to require 
another 4 or 5 years of data collec- 
tion before we know. By then. DAN 
will probably have enough data to 
make some more rigid statements 
about that. So, I think there are two 
sides. I mean, there are guvs who 
have flown within 10-12 hours after 
diving and have not gotten bent. I 
doubt that we're going to alter thai 
behavior. And, then there are other 




guys who nov\ wait. I wail because 
getting bent is not worth it to nie. 

1. Sheffield PJ, ed. Flying utter diving. 
thirty-ninth undersea and hyperbaric 
medical society workshop. Bethesda 
MD: Undersea and Hspcrbaric Med- 
ical Society, 1989:164. 

2. Bennett PB. DAN resolution ot tlying 
after diving guidelines. In: Nichols G, 
ed. Alert di\er. Durham NC: Divers' 
Alert Network, l992;SeptyOct:2. 

Mathews: I believe there's some 
suggestion in the literature that if 
you've had decompression sickness 
once, you're more prone to it in the 
future. Is that correct? 
Weaver: Yes, that's correct, and 
some data support that hypothesis. 
It's not exactly clear, though. Is it 
because the diver who got bent once 
may have been pushing things and 
continues to push things'? The data- 
base is not as tight as we would like 
it to be. 

Mathews: Getting back to the cham- 
bers themselves, what type of train- 
ing or skills should the individuals 
who are operators or workers in 
chambers have? 

Weaver: That's a good question. I 
think it depends on the setting — 
multiplace or monoplace chamber. A 
Hyperbaric Medicine Technology 
Board and Examination have been 
established; so, you have to have 
either recognized 'grandfather' cre- 
dentials or training-course cre- 
dentials, plus passage of the exam. 
The first exam was given in June 
(1991). At our hospital, we are 
requiring all of our hyperbaric ther- 
apists to pass that examination. 
There's no consensus out there 
among the other groups, but I believe 
that most groups want the people 
operating the chamber to have some 
minimal qualifications. Many of the 
large multiplace chambers are run by 
people who have extensive expe- 
rience from the military but don't 
have formal credentials, other than 

having retired from the Navy where 
they ran a chamber for 20 years. 
We're trying to formalize creden- 
tialing, especially at the nonphysi- 
cian caregiver level. 
Stoller: Can you comment on the 
prevalence of oxygen toxicity and 
the impact of the brief interruption 
w ith air on that likelihood? 
Weaver: Considerable work has 
looked at both pulmonary and central 
nervous system oxygen toxicity in 
the hyperbaric environment in hu- 
mans.' They looked at reduced FVC 
and also the incidence of seizures in 
young healthy men and have shown 
that they are directly related to pres- 
sure and duration — higher pressure, 
shorter duration. By giving inter- 
mittent doses of air. you can reduce 
the incidence or at least lengthen the 
duration of exposure before you see 
those problems. That's also been 
borne out in animal studies. 1 think 
questions about oxygen toxicity 
remain unanswered (and I make that 
statement also as a critical care phy- 
sician). We have completed a pros- 
pective randomized study in ARDS 
patients, in which half of our patients 
received extracorporeal carbon diox- 
ide removal and half received con- 
ventional ventilator support. The 
oxygen concentrations in many of 
those patients was between 0.7 and 
1.0, for prolonged periods of time 
(just as was mentioned earlier), and 
we have long-term follow-up data 
about lung function. About half of 
the patients in both groups survived. 
At 1-year follow-up, their lung func- 
tion reflected a restrictive pathology, 
but it doesn't intertere with function, 
about 609c restricted by predicted 
values. So. oxygen toxicity is cer- 
tainly something we worry about, but 
I'm not sure that it's very important 
practically. I don't usually put people 
in the chamber who require more 
than 50 or 60% oxygen, and if I do I 
usually do blood gases because I 
can't oxygenate some of those pa- 
tients in the chamber. For example, if 

they require 60% oxygen at almos- 
jiheric pressure for adequate arterial 
oxygen pressure, even at ? atmos- 
pheres the P(); may be only 500 or 
600 ton-. 1 feel that I'm probably not 
accomplishing anything, so I don't 
treat those patients. 1 looked at blood 
gases before and after hyperbaric 
oxygen in patients with abnormal 
lung function whom we have treated 
with hyperbaric oxygen. We have 
hundreds of data points, and there 
was basically no change, no altera- 
tion at all, in the a-A ratio.- People 
have argued that when you put them 
in a hyperbaric chamber, their lungs 
will get worse because of absorption 
atelectasis, and you will potentiate 
oxygen toxicity, and their blood 
gases will be worse — but they really 
aren't. That's true of people with 
normal as well as abnormal lungs; 
so, I can't tell you what the risk is. 
We are very aggressive in using air 
breaks. All multiplace chambers use 
air breaks; most monoplace cham- 
bers do not. Toxicity doesn't seem to 
be a big problem. Again, the risk of 
seizures is I in 5,000, and pulmonary 
O: toxicity is virtually something we 
don't see because our schedule is 
quite intermittent — one or two treat- 
ments a day. 

1. Clark JM. Oxygen toxicity. In: Ben- 
nett PB, Elliott DH, eds. The physiol- 
ogy of medicine and diving. 3rd ed. 
London: Bailliere. Tindall. and Cox, 

2. Weaver LK. Howe S. Arterial oxygen 
tension of patients w ith abnormal pul- 
monary function during hyperbaric 
oxygen therapy (abstract). Undersea 
BiomedRes 1991 ;18(Suppl|: 107-108. 

Galvin: You indicated earlier that no 
■goe)d' ventilator is available for use 
in hyperbaric chambers at this time. I 
wonder if we could revisit that issue 
just for a moment, and identify the 
specific features that you feel should 
be incorporated into a ventilator for 
hyperbaric therapy. 




Weaver: OK. I think that's really a 
two-pan question, one for multiplace 
and one tor monoplace chambers. 
The technical limitation with the 
monoplace chamber is that the ven- 
tilator's in the chamber but the oper- 
ator is outside; so, there has to be 
some pass-through mechanism, where- 
by you can control the ventilator. 
Also, the ventilator in a monoplace 
environment has no alarms — no feed- 
back alarms. You're sitting there 
watching it. If you get distracted by 
something that goes on with the 
patient or a telephone call or what- 

ever, you may miss something. Oth- 
ers have described the "ideal" hyper- 
baric ventilator.' We have used our 
own transport \entilator. which is a 
highly modified Bird ventilator that 
MarDiene (Jeffs) will talk about 
later. We"ve used it inside the cham- 
ber, and it works very well. The 
problem is the four knobs to turn. We 
have to figure out how to turn four 
knobs from outside the chamber. In 
the multiplace chamber, flow resis- 
tance is still a big problem, but you 
can probably overcome it by making 
ventilators that work at much higher 

dri\ ing pressures than 50 or 60 psi. 
But the ventilator then has to be able 
to accept a driving pressure of 150 
psi, for example. Inside the multi- 
place chamber it"s easy because you 
can control knobs and things. So, 
those are briefly the two problems as 
1 perceive them. 

Blanch PB. Desautels DA. Gallagher 
TJ. Deviations in function of me- 
chanical ventilators during hyperbaric 
compression. Respir Care 1991;36: 



Monitoring during Resuscitation 

Dean Hess MEd RRT and David Eitel MD 


Extensive and sophisticated cardiopulmonary 
monitoring is commonly used in critically ill 
patients.'- During cardiopulmonary resuscitation 
(CPR), however, monitoring is frequently limited 
to electrocardiography, episodic blood pressure 
determination, and non-real-time measurements of 
arterial blood gases and pH. For both technical and 
traditional reasons, other forms of monitoring are 
not commonly used, particularly during the early 
stages of the resuscitation.^ In this paper, we 
review the literature of monitoring during resus- 
citation and make some recommendations for the 
practical application of this monitoring. The prin- 
cipal, but not exclusive, focus of the paper is mon- 
itoring during resuscitation in the context of adult 
sudden cardiac death. The outcome of resus- 
citation, both prehospital and in-hospital, is also 


The most common, and some would say the 
most useful, monitor during cardiopulmonary 

Mr Hess is Assistant Director, Department of Research, York 
Hospital, and Instructor, School of Respirator)' Therapy. York 
Hospital and York College of Pennsylvania. Dr Eitel is Res- 
idency Director. Department of Emergency Medicine. York 
Hospital — York. Pennsylvania. 

A version of this paper was presented by Mr Hess on October 
4, 1991, during the Respirator'.' Care Journal Conference on 
Emergency Respiratory Care held in Cancun, Mexico. 

Reprints: Dean Hess, Department of Research. York Hospital, 
York PA 17405. 

resuscitation is the electrocardiogram (ECG). ECG 
monitoring allows rhythm detection and evaluation 
of treatment (eg, defibrillation, external pacing). 
Recommendations for use of the ECG during cardio- 
pulmonary resuscitation have been widely promul- 
gated by the American Heart Association and are 
beyond the scope of this paper.^ Automated defib- 
rillators are now being used by emergency medical 
technicians (EMTs) in the field, with generally 
good results.'' '- Initial experience with defib- 
rillation by EMTs has been positive when there is 
an assessment of the system's response in the set- 
ting of adult sudden cardiac death and when EMT- 
defibrillators are placed on rapid response vehicles 
(ie, < 10 min average response time). Further, use 
of semi-automated defibrillators in a surveillance 
mode during Basic Life Support (BLS) transpo:1 of 
high-risk medical patients has proven beneficial. 

It is important to appreciate that an adequate 
rhythm on ECG has no relationship to cardiac out- 
put. That is, the ECG is not an indicator of blood 
flow. Arterial blood pressure and palpation of aile- 
rial pulses are commonly used as indexes of blood 
flow during resuscitation. However, these are also 
unreliable. It is for this reason that some inves- 
tigators have explored the use of transcutaneous 
monitors, conjunctival monitors, and capnography 
during CPR to evaluate cardiac output.'' 

Tidal Volume and Respiratory Rate 

Tidal volume monitoring in a breath-by-breath 
manner has become routine during the ventilation 
of critically ill apneic patients. When apneic 
patients are ventilated during CPR, however, tidal 
volume is almost never measured. Nearly every 
commercially available bag-valve resuscitator is 




designed to allow a spirometer to he attached for 
measurement of exhaled volumes, and any hand- 
held spirometer (such as those used for measure- 
ment of weaning parameters) can be used (Fig. 1 ). 
Numerous studies have shown that the volumes 
deli\ered from a bag-val\e resuscitator are affected 
by many factors. These include resuscitator 
brand,''' lung compliance and resistance,'"* whether 
one hand or two hands are used to squeeze the 
resuscitator,"'"' and hand size.""' Several studies 
have also shown that bag-valve-mask ventilation 
delivers lower volumes than exhaled \entilation 
techniques (mouth-to-mouth and moulh-to-mask).'^""^ 
Problems associated with bag-valve-ventilation 
technique have also been reported during patient 
transport.-' -'' 

Fig. 1. Adult bag-valve resuscitator with respirometer. 

To our know ledge, there is only one report in the 
literature of the use of a spirometer during the 
resuscitation of adult patients.-' Ornato et al used a 
Wright respirometer to measure tidal volumes dur- 
ing the resuscitation of 45 adult intubated patients. 
CPR was performed using a mechanical device 
(Thumper. Michigan Instruments. Houston TX). 
The pressure setting on the Thumper was adjusted 
to maintain a tidal volume of 10 niL/kg. Ornato 
et al found that relatively high pressures, 43 ± 8 
cm H^O, were required to deliver tidal volumes of 
936 ± 322 mL (compliances of 0.022 ± 0.02 L/cm 
H2O) and suggested. "Routine measurement of Vr 
in the cardiac arrest patient after intubation is a 
suiiple procedure v\hich can be perlt)rmed with 
minimal equipment in any hospital." Others ha\c 
shown thai monitoring of tidal volumes is useful 
during hag-\alve ventilation of adult patients dur- 
ing in-hospital transport.-^ -" 

Research is needed on tidal volume monitoring 
during adult resuscitation. We suggest the fol- 
lowing as important research questions: 

• Is it practical to measure tidal volumes during 
the resuscitation of intubated adults? 

• What tidal volumes are typically delivered 
during bag-valve ventilation of adult intu- 
bated patients during resuscitation? 

• Could a simple device be constructed to indi- 
cate adequate tidal volume delivery during 
resuscitation (eg, > 800 niL versus < 800 mL, 
per American Heart Association standards-^)? 

• Does monitoring tidal volume during resus- 
citation affect outcome? 

The American Heart Association recommends a 
respiratory rate of 12/min during the resuscitation 
of adult patients.^ It has been our experience that 
respiratory rates greater than this are commonly 
used by respiratory therapists and prehospital pro- 
viders. Although therapists and paramedics have a 
\ariety of explanations for this practice, we believe 
it is an attempt to increase ventilation in spite of 
difficulties in delivery of an adequate tidal volume, 
in the attempt to lower Pco: to control acid-base 
balance. Potential problems related to the use of 
higher respiratory rates during resuscitation include 
(1) a higher rate requires a higher tlow to deliver 
the same \olume. w hich increases the risk of gas- 
tric insufflation m nonintubated patients;-' (2) 
higher rales also decrease the refill time of the bag- 
valve resuscitator. which can decrease the deliv- 
ered oxygen concentration:'" and (3) in patients 
with a high dead-space-to-tidal-\olume ratio. Vp/ 
Vt, as may occur during cardiac arrest, increasing 
the respiratory rate maN ha\e minimal effect on 
alveolar ventilation. 

The efficiency of bag-val\e-mask ventilation has 
also been evaluated in infants, with conflicting 
results. Milner et al" found that bag-valve-mask 
\enlilation at birth was very inefflcient. However, 
Kanter'- and Terndrup et af^' found that a bag- 
\alve-mask could be used effecti\el\ with infants. 
Whether mcasuicment of tidal volumes is clinicallv 
useful in infants may be a moot point because no 
spirometer is available at this time (1992) to reli- 
ably measure the small tidal vcilumes in these 




Ventilation Pressures 

Just as monitoring of tidal volumes during resus- 
citation may be useful in adults, monitoring of ven- 
tilation pressures may be important during the 
resuscitation of infants. Such monitoring may be 
important to avoid pressure-related injury to the 
lungs, and to avoid gastric insuftlation in non- 
intubated infants. Although a method to monitor 
airway pressures during use of infant resuscitator 
bags was reported about 10 years ago.'''* manom- 
eter-guided \entilation of infants may yet not be 
commonly used.^^ 

Finer et al"*^ found that the pressure-relief ("pop- 
off ) valves supplied on commercially available 
infant resuscitators were unreliable, and that there 
was a decrement in delivered oxygen concentration 
when the pop-off valve was acti\ ated. Goldstein et 
al ''~ e\ aluated the use of pressure manometers dur- 
ing manual \entilation of newborn infants and 
found that peak airway pressures were significantly 
lower when an in-line manometer was used (Fig. 
2). Although that study was conducted in a non- 
cardiac-arrest setting, it seems reasonable to extra- 
polate these finding to patients in cardiac arrest. 

14 f- 




















-6 l- 


Fig. 2. Peak inspiratory pressures (PIP) during manual 
ventilation of 1 1 neonates, with and without a mano- 
meter. (Reprinted, with permission, from Reference 35.) 

Kauffman and Hess-''' described a system to 
adapt an aneroid manometer to an infant Laerdal 
resuscitator (Fig. 3). Even though it has been 




Fig. 3. Modified infant resuscitator with pressure manom- 
eter (A), connecting tubing (B), threaded nipple adapter 
(C), and resuscitator (D). (Reprinted, with permission, 
from Reference 34.) 

shown that the pop-off valves on infant resus- 
citators are unreliable, this system has been crit- 
icized because it eliminates the pop-off. Nipple 
adapters are now commercially a\ ailable that allow 
a manometer to be attached between the resus- 
citator and the endotracheal tube (Fig. 4). Although 
this adds a small volume of dead space, the pop-off 
svstem remains intact. 





Fig. 4. Pressure manometers attached to the outlet of 
commercially available resuscitators. 

Endotracheal Tube Position 

An endotracheal tube provides the best airway 
during CPR. and we believe that \ irtually everyone 
would agree that the patient should be intubated as 
soon as possible during resuscitation.^ Malposition 
of the endotracheal tube can be catastrophic if 
unrecognized. Intubation of the esophagus results 
in hypoxemia, respiratory acidosis, and gastric dis- 




tention."' Intubation of a main-stem bronchus can 
result in collapse of the unvenlilated lung, hypox- 
emia, and hyperinflation of the ventilated lung.^^ 
During CPR. assessment of correct endotracheal 
tube position usually includes ascertaining that the 
tube passes through the \ocal cords during intuba- 
tion, observation of symmetric chest expansion, 
chest auscultation of symmetric bilateral air entry, 
auscultation of the abdomen for absent gastric 
insuftlation sounds, ease of ventilation (lung com- 
pliance), and condensation on the inside of the 
endotracheal tube. As shown by Brunei et al,'** clin- 
ical signs of tube location can be unreliable for 
confirming endotracheal tube placement. They 
compared the use of clinical findings and chest 
roentgenograms in 219 critically ill patients and 
found that 14'^/ of the patients required repo- 
sitioning of the endotracheal tube and 5% had 
main-stem intubations. They also found that endo- 
bronchial intubation was more common in female 
than in male subjects, usually occurred after emer- 
gency intubation, and occurred in the majority 
despite the assessment of equal and bilateral breath 

Conrardy et al evaluated the effects of flexion 
and extension of the neck on endotracheal tube 
position. ^"^ They found that the tube moved an aver- 
age of 1.9 cm toward the carina with neck llexion, 
1 .9 cm away from the carina with extension of the 
neck, and 0.7 cm away from the carina with lateral 
positioning (Fig. 5). With extension of the neck 
from a neutral position, they found that the endo- 
tracheal tube could nunc as much as 5.32 cm. The 
route of intubation (oral versus nasal) and the intla- 



1 li 







\ 12^3 


^ 1 

Mean Tube 
Movement in 







■ 5.2 

Fig. 5. The mean endotracheal tube movement with flex- 
ation and extension of the neck from a neutral position. 
(Reprinted, with permission, from Reference 39.) 

tion status of the cuff did not affect the distance 
that the endotracheal tube moved with neck flexion 
and extension. This study has important implica- 
tions tor CPR because patients are frequently 
mo\ed during the resuscitation procedure (eg. bed 
to litter, litter to bed, litter to diagnostic table). 
Thus, a correctly placed tube may quickly become 
an incorrectly placed one. Endotracheal tube posi- 
tion should be reassessed eveiy time the patient is 
moved. The effects of flexion and extension of the 
neck on movement ol the endotracheal tube have 
also been demonstrated by Toung et al.'*" 

Although the chest radiiigraph remains impor- 
tant for assessment of endotracheal tube position, it 
suffers the limitatit)n of requiring a considerable 
time lapse between the time of intubation and the 
a\ailability of the chest radit)graph for evaluation. 
Further, a chest radiograph is not practical during 
resuscitation (particularly if chest compressions are 
being applied) and is not available in some loca- 
tions (such as the preho.spital environment). 

Use of the Tube Markings To .4ssess 
Tube Placement 

Owen and Cheney" evaluated the use of the 
marks printed on the side of the endotracheal tube 
to properly place oral lubes in 57H adult criticall\ 
ill patients. They found that securing the tube at the 
upper incisor teeth or gums at the 23-cm mark in 
men and the 2 1 -cm mark in women significantly 
reduced the likelihood of inadvertent endobronch- 
ial intubation. .-Mthougli we belic\e that this 
method is useful as a general guide, it must be 
appreciated that there is considerable variabilit\ in 
the anatoniN of the upper respirator) tract. The 
measurements on the tube should always be used in 
conjunction with other means of assessing tube 
placement (eg, clinical parameters, chest radiog- 
raph) ). During CPR, noting the depth of the lube at 
the teeth or gums by reference to tube marks can 
also be useful for detecting movement of the tube. 

Use of Capnofiraph) lo Assess 

Tube Placement in Patients Not in .\rrest 

Esophageal intubation is a serious problem.^- It 
can occur at the time of intubation, during manip- 
ulation of the endotracheal tube, or durinc mo\'e- 




merit of the head.'*'^'*'' Esophageal intubation can be 
difficult to recognize, particularly in obese patients 
or in patients in whom the vocal cords cannot be 
easily visualized. Of the methods available to 
detect esophageal intubation, measurement of 
Petco: is regarded as the most reliable, and it has 
been suggested that Pctco: should be used routinely 
to determine proper endotracheal tube positions- 
Murray and Modell. using dogs not in cardiac 
arrest, found PetCO: useful for the recognition of 
esophageal intubation.'" Monitoring of esophageal 
Pco; produced very low levels of Peico; (Fig. 6). 
Total obstruction of the endotracheal tube also 
resulted in a drop in Petco:, and evaluation of the 
capnographic wavefonn was useful in the detection 
of partial obstruction of the endotracheal tube. 
Mo\ement of the endotracheal tube from the tra- 
chea into the pharvnx resulted in changes in the 




K < 

lU -J 


Ui X 

> < 

X •" 

o s 





O o 



< H 

a o 


K Z 

3 K 


K = 

K U. 






ifi 4- 

1 1 1 1 1 


N 3- 



O 2- 

I \\ H 


O 1- 

ILm . 


Fig. 6. Differences in end-tidal Pco2 witfi endotracfieai 
tube in tracfiea and in the esophagus. (Reprinted, with 
permission, from Reference 43.) 

In a study of 20 patients not in cardiac arrest, 
Linko et al found Petco: useful in the detection of 
esophageal intubation.^ They did find that esoph- 
ageal Pco2 could be quite high (nearly 57() fol- 
lowing exhaled gas ventilation with associated 
inadvertent gastric distention. However, the esoph- 
ageal Pco: dropped to < 29c following six ventila- 
tions of the stomach. Guggenberger et al''"' reported 
rapid detection by capnography of accidental 
esophageal intubation in 21 patients not in cardiac 
arrest during anesthesia. 

Zbinden and Schupfer"*'' reported a case in which 
the capnogram revealed a pattern compatible with 
tracheal intubation for a few breaths following 
esophageal intubation in a child who had ingested 
carbonated beverage before intubation. Garnett et 
al''^ evaluated the effects of ingested carbonated 
beverages on esophageal Pcoi- They instilled beer 
into the stomach of dogs, and compared esophageal 
Pco2 to tracheal Pco2- Ingestion of the carbonated 
beverage resulted in an increased esophageal Pco:, 
but there was a rapid decrease in this esophageal 
Pc02 following 10-15 seconds of gastric ventila- 
tion. Thus, high gastric Pco:S were quickly washed 
out, allowing Petco: to be useful in detection of 
esophageal intubation following ingestion of car- 
bonated beverages, in this model not in cardiac 

Owen and Cheney*** have reported the usefulness 
of a CO2 apnea monitor to detect esophageal intu- 
bation. This method is qualitative rather than quan- 
titative, in that only the presence or absence of COi 
is detected. This device offers the advantage of 
lower cost than capnography but suffers a sig- 
nificant limitation in that it does not provide either 
a capnographic waveform or a display of Petco:- 
Other portable battery-operated COt monitors (eg, 
MiniCAP. MSA Catalyst Research. Owings Mills 
MD) are also available to confirm endotracheal 
intubation; these devices'*' are convenient to use 
outside of the operating room because they are sim- 
ple to use, they do not require calibration, and they 
have no warm-up time. Such devices may prove to 
be particularly useful to prehospital providers in 
the field. However, no data are yet available related 
to their use in the field, and their ability to detect 
end-tidal CO2 during cardiac arrest needs further 

Generally, it has been felt that capnography can- 
not discriminate between endotracheal and endo- 
bronchial intubation. However, Gandhi et aP 
reported a case in which Peico; decreased from 28 
torr to 22 torr following movement of the endo- 
tracheal tube from the trachea into the right main- 
stem bronchus in an anesthetized patient. This 
effect was then duplicated in a canine model. These 
authors attributed this effect to an increase in V/Q 
(the ventilation-to-perfusion ratio) to the ventilated 
lung, resulting in a decrease in Petco:. Further 
work is needed to determine the usefulness of cap- 
nography to detect main-stem intubation. 




Several limitations of the use ot" Pcico: to detect 
esophageal intubation must be recognized. First, 
significant levels of CO; can be present in the 
stomach following exhaled gas ventilation or inges- 
tion of carbonated beverage. Howexer. this CO, is 
quickly cleared with esophageal ventilation.^' Sec- 
ond, exhaled CO; from the lung can be very low in 
the presence of low puhnonary perfusion. Mon- 
itoring of Peico: to detect esophageal intubation 
may be of limited usefulness in the presence of car- 
diac arrest and low-tlow states, despite the finding 
that PetCO; may detect esophageal intubation in the 
presence of cardiac arrest in dogs."'' Also, cap- 
nography cannot be used to confirm endotracheal 
lube placement if exhaled gas ventilation is being 

The Fenem End- Tidal CO Detector 
To Assess Tube Placement 

tidal CO, nn)nitoring using the Fenem was a safe, 
reliable, rapid, simple, and portable method for 
determining endotracheal tube position. In that 
study of patients not in cardiac airest. the Fenem 
confirmed tracheal intubation and detected esoph- 
ageal intubation 100% of the time. Anton et a!''' 
evaluated the Fenem in 60 hospitalized adult 
patients undergoing intubation. They found that the 
sensitivity for detection of tracheal placement was 
nearl\ 100% for patients in respiratory failure, but 
was not as good for patients in cardiac arrest. Mac- 
Leod et aP^ evaluated the use of the Fenem during 
250 emergency intubations, and compared its use 
to clinical parameters of endotracheal tube posi- 
tion. In that study, it was found that the sensitivity 
was greater for tracheal intubation in patients not in 
cardiac arrest ( 1007f ) than patients in arrest (72%), 
but that the specificity was greater in patients in 
arrest (100%) than patients not in arrest (86%). 

Simple colorimetric techniques to evaluate the 
presence of CO; in exhaled gas have been available 
for more than .SO years. In 1916. Marriott"- 
described the use of phcnolsulphonephthalein. 
which produced a color change in the presence of 
CO;. By collecting alveolar gas. subjecting that gas 
to the indicator, and comparing with color stan- 
dards, Marriott was able to determine the con- 
centration of alveolar Pco;- In 19.S9. Smith and 
Volpitto"' described a barium h\droxide pre- 
cipitation reaction that could be used to evaluate 
alveolar CO; concentration, in 1984. Berman et af'* 
described the "Einstein Carbon Dioxide Detector." 
which uses cresol red and phcnothalein to produce 
a color change from red to \cllo\\ in the presence 
of exhaled CO;. The}, suggested that this device 
might be useful to confirm tracheal intubation or to 
detect esophageal intubation. 

A portable non-electronic disposable de\ ice has 
become commercially available to qualitatively 
detect end-tidal CO; (Fig. 7. Fenem. New York 
NY: now EasyCap, Nellcor. Hayward CA).'' '' It is 
designed to produce a color change (colorimetric 
end-tidal CO; detection) in the presence of exhaled 
CO;, and bench evaluation has indicated that it pro- 
duces appropriate color changes over a w ide range 
of P(();S and ventilatory patterns.''' In a study of 62 
intubations in anesthetized patients not in cardiac 
arrest, Goldberg el al''- found that colorimetric end- 

Fig 7 Fenem End-Tidal CO2 Detector between bag- 
valve resuscitator and endotracheal tube. 

Others ha\e found that the Fenem was less reli- 
able ill the detection of esophageal intubation in 
patients in cardiac arrest.*'' '" We e\aluated the 
Fenem End-Tidal CO; Detector in 30 patients in 
cardiac arrest in the field." All patients were intu- 
bated, and correct endotracheal tube position was 
confirmed b\ t)bser\ ation of the endotracheal tube 
passing through the vocal cords and by clinical 
assessment (eg. auscultation of the chest and epi- 
gastrium). Cyclic color changes were noted on the 
Fenem in only 9 of 30 cases (sensitivity for detec- 
tion of tracheal intubation of 30%). Although the 
Fenem may be useful to confirm tracheal intuba- 


RliSPIRA iOR^' CARE • JUL^ 92 Vol 37 No 7 


tion ill patients not in cardiac arrest, it is much loss 
reliable in the cardiac-arrest state, which is most 
likely due to inadequate pulmonary blood tlow. 

Use of the Fenem during intraht)spital transport 
of mechanically ventilated patients not in cardiac 
arrest has also been described, and may be useful to 
detect ventilator disconnection and airway mis- 
placement in such patients during transport." The 
Fenem can only be used for a short time (several 
hours at most): it becomes ineffecti\e in the pres- 
ence of humidity in the patient's exhaled gas and 
by contamination with pulmonar\ edema fluid and 
drugs administered endotrachealiy. 

Very little has been reported related to the use of 
the Fenem in infants and children. In children aged 
1 day to 17 years (weighing 1.0 to 70.0 kg). 
Bhende et al - found the device sensitive and spe- 
cific in verifying endotracheal tube position in the 
presence of spontaneous circulation using episodic 
sampling. These results were later confirmed in 
newborn piglets.^' Because the dead space of the 
Fenem is 38 mL. it should not be used for continu- 
ous monitoring in spontaneously breathing children 
because of the potential risk of rebreathing. " 

Use of the Lighted Stylet To Assess 
Endotracheal Tube Position 

Use of a fiberoptic bronchoscope allows accu- 
rate determination of endotracheal tube position. ^'' 
However, this method is not practical in the emer- 
gency setting, and is not performed by non- 
physicians. The use of a lighted stylet (sometimes 
called a light wand) has been described to aid in 
orotracheal and nasotracheal intubation. ^^■'*" The 
lighted stylet can also be used for detection of 
esophageal or endobronchial intubation.'*'"'*'' 

Several styles of the lighted stylet can be used 
(Concept Inc. Clearwater FL). The Flexi-Lum flex- 
ible sursical lisht has a 25-cm semitlexible ricid- 

wire portion, with a handle containing the battery 
at one end and a light at the other end (Fig. 8). The 
Tube-Stat Orotracheal Intubation Stylet is similar 
in design to the F'lexi-Lum. and is intended for use 
with orotracheal intubation (Fig. 9). With either the 
Flexi-Lum or the Tube-Stat Orotracheal Intubation 
Stylet, the semitlexible rigid-wire portion can be 
bent to change the curvature of the endotracheal 
tube, and thus facilitate intubation. The Tube-Slat 
Nasotracheal Intubation Stylet (Fig. 9) is designed 
to facilitate nasotracheal intubation. It differs from 
the Flexi-Lum and the Orotracheal Intubation Sty- 
let in that it is more flexible and has a longer flex- 
ible portion (.^.3 cm \'ersus 25 cm). 

Fig. 8. Flexi-Lum flexible surgical light. 

Fig. 9. Tube-Stat Orotracheal Intubation Stylet (top) and 
Nasotracheal Intubation Stylet (bottom). 

When a lighted stylet is used and the endo- 
tracheal tube is in the trachea, a glow (trans- 
illumination) should be seen in the region of the 
laryngeal prominence and sternal notch (Fig. 10). If 
the endotracheal tube is positioned in the esoph- 
agus or a main-stem bronchus, the light is either 
not seen or is dull and diffuse. Decreasing the 
ambient light and applying cricoid pressure facil- 
itates visualization and transillumination. 

Most of the reports in the literature of the use of 
a lighted stylet describe its use at the time of intu- 
bation.^'^ **" However, several reports describe its 
use to determine optimal tube placement following 
intubation. '*''^^ Stewart et al**- used the lighted stylet 
to determine correct endotracheal tube position in 
10 human cadavers and concluded that use of a 
flexible lighted stylet can guarantee accurate and 
consistent placement of the endotracheal tube at an 
appropriate position above the carina. One of us 

RESPIR.^TORY C.-\RE • JULY "92 Vol 37 No 7 



Fig. 10. Transillumination of the sternal notch produced 
by lighted stylet in correctly positioned endotracheal 

(Hess) and Shaikh^' evaluated the use of a lighted 
stylet to assess endotraeheal tube position in 60 
adult eritieallN ill patients and found that the Tube- 
Stat Nasotracheal Intubation stylet was superior to 
the Fle.\i-Lum. The Flexi-Lum could not be passed 
through the endotracheal tube in 5 of 45 (I l'7f) of 
cases, and transillumination was observed in 37 of 
the 40 patients (93%) in whom it could be passed. 
The Tube-Stat Nasotracheal Intubation Stylet could 
be passed in 15 of 15 in which it was used, 
and transillumination was observed in each case. 
We found that cricoid pressure and a darkened 
room facilitated transillumination and conclude 
that the Tube-Stat Nasotracheal Intubation Stylet is 
more useful than the Flexi-Lum in patients who are 
already intubated, and that a lighted stylet may be 
useful to assess tube position in many intubated, 
critically ill patients.'*' 

Use of the Esophageal Detector Device 
To Assess Endotracheal Tube Position 

In the late 1980s, several papers described the 
use of an esophageal detector de\ ice (HDD) to dis- 
tinguish between endotracheal and esophageal intu- 
bation.^'''^*' This is a simple device, consisting of a 
syringe (Fig. 1 1 ) or squeeze bulb (Fig. 12) attached 

Fig. 11. Syringe attached to an endotracheal tube to 
serve as an esophageal detector device. 

to the endotracheal tube. If the endotracheal tube is 
in the trachea with the cuff deflated, gas can be eas- 
ily aspirated from the tube with minimal resistance. 
However, if the tube is in the esophagus, there is 
marked resistance to aspiration of gas from the 
tube. In studies conducted with anesthetized 
patients, the HDD has been found to be 100% accu- 
rate in differentiating between tracheal and esoph- 
ageal intubation.'*'*"***' 




Fig. 12. Prototype squeeze-bulb esophageal detector 
device (SuctionEasy, Respironics. Murrysville PA). 

Oberly et al"'^ evaluated the use of the HDD m 
the bodies of 10 recently deceased adults in the 
emergency department. In that study, endotracheal 
tubes were passed into the trachea and into the 
esophagus of these subjects, and advanced life sup- 




port providers (physicians, nurses, paramedics, and 
respiratory therapists) blinded to tube position were 
asked to use the EDD to identity which tubes were 
in the trachea and which were in the esophagus. In 
45 trials conducted on the 10 bodies, the EDD cor- 
rectly indicated tracheal and esophageal intubation 
in all cases. 

In children 1-10 years of age, the .syringe EDD 
was used to correctly identify tracheal and esoph- 
ageal intubation.*' Similar results were reported in 
20 children 5-10 years of age.*" However, a mod- 
ified EDD (5-mL syringe rather than a 60-mL 
syringe) was found unreliable in 20 infants less 
than 1 year of age.''" These studies suggest that a 
syringe EDD may be useful with uncuffed endo- 
tracheal tubes in children over 1 year of age. but 
the EDD may be less reliable in children less than 1 
year of age. To our knowledge, there has been no 
report of the use of a .squeeze-bulb EDD in chil- 

More work is needed to evaluate the use of the 
EDD following emergency intubation. More work 
is also needed to evaluate the EDD in pediatric 
patients. However, the literature thus far suggests 
that the EDD might be a simple, inexpensive, and 
reliable method to detect esophageal intubation in 
non-arrested and arrested patients. The use of this 
device is particularly attractive in places such as 
the prehospital environment, where capnography is 
not readily available. 

Use of the Trach-Mate Intubation System 
To Assess Endotracheal Tube Position 

Fig. 13. (A) Trach-Mate with metallic element embedded 
within the tube wall (arrow): (B) portable locater instru- 
ment. (Reprinted, with permission, from Reference 93.) 

The Trach-Mate intubation system (McCormick 
Laboratories, North Chelmsford MA) is used in 
infants and children (endotracheal tube sizes 2.5- 
5.5 mm ID). It consists of an endotracheal tube 
with a magnetic metallic marker at a defined dis- 
tance from the distal tip of the tube. A portable, 
battery-operated locater is capable of detecting the 
marker transcutaneously (Figs. 13 & 14). The 
locater probe is placed at the upper edge of the ster- 
nal notch perpendicular to the skin, and the endo- 
tracheal tube is moved until maximal audible sound 
and light signals are obtained. Two studies have 
evaluated the use of this device, and both found it 
useful to determine correct endotracheal tube posi- 



Fig. 14. Use of Trach-Mate to determine endotracheal 
tube position. (Reprinted, with permission, from Refer- 
ence 93.) 

Evaluation of Perfusion during Resuscitation 

Cardiac output and other invasive measurements 
of blood flow often might be useful during resus- 
citation. However, invasive measurements such as 
these are usually not feasible during resus- 
citation.'^ For that reason, noninvasive indices 
(capnography, transcutaneous P02, conjunctival 
Po:) of perfusion have been evaluated during resus- 





It has been known tor many \cais that decreased 
pulmonary blood flow (ie. cardiac output) results in 
decreased Pcico:-'"'''^ Because Peico: is determined 
by the V/Q. if ventilation is held constant then 
changes in blood flow will be reflected by changes 
in PeiCO: ■ 

Porcine.'^-"" canine."""'^ ovine."" and rat'"-' mod- 
els of cardiac arrest have suggested that Petco: is 
useful in the evaluation of the effectiveness of 
CPR. Typically, the onset of cardiac arrest results 
in a drop of Pcico: to zero. With the initiation of 
CPR. there is an increase in Petco:- PeiCO: cor- 
relates with cardiac outpul (ie. pulmonary blood 
flow) during CPR.'"^ as well as coronary perfusion 
pressure (CPP = aortic pressure - riszht atrial pres- 

Many studies report the usefulness of Peico: dur- 
ing resuscitation of humans."" '"* Kalenda'"'' ob- 
served that Pctco; decreased v\hen a rescuer 
became fatigued and that Petco: increased when 
resuscitation was continued with another rescuer. 
Garnett et al"* evaluated Pctco: in 2? paients fol- 
lowing cardiac arrest and found that Peico: 
increased immediately in patients who had a return 
of spontaneous circulation. Similar results were 
reported by Falk et al"'' in an evaluation of 13 epi- 
sodes of cardiac arrest in 10 patients (Fig. 15). 

One of the exciting results from animal studies 
on the use of Petco: during CPR is the reported use- 




/ .-; 

(N = 12) 

(N = 13) (N = 13) 


(N = 7) 

fulness of PetCO; as a prognosticator of resus- 
citability."" "'^ Animals who are successfully resus- 
citated typically have a higher Petco: during resus- 
citation. Thus, a very low Peico: during CPR is not 
likely to be associated with a positive outcome. 
-Sanders et a!"'** found that Peico; during CPR was 
also useful in the identification of patients likely to 
be resuscitated. In that study, patients who were 
resuscitated had a PetcO: of 15 ± 4 torr during 
resuscitation, but patients who were not resus- 
citated had a PetCO: of only 7± 5 torr (Fig. 16). 
Similar findings have been reported by Callaham 
and Barton.'" ""• They found thai an initial Pcico: 
of 15 torr during resuscitation correctly identified 
719f of the patients who were successfully resus- 
citated, with a specificity of 987c. Martin et al."* 
however, found that PeicO: was a less reliable indi- 
cator of CPP in dogs in cardiac arrest following 
epinephrine administration and suggested that 
PetCO; be used w ith caution as an indicator of CPP 
following epinephrine administration. 

30 r 








Fig. 15. Changes in end-tidal COp during resuscitation. 
(Reprinted, with permission, from Reference 107.) 

Resuscitated Nonresuscitated 

Fig. 16 Average end-tidal Pco2 of 9 resuscitated 
patients and 26 nonresuscitated patients. (Reprinted, 
with permission, from Reference 108.) 

We" e\ aluated the use of the Fenem during car- 
diac arrest in .^0 prehospital patients to predict 
patients likely to have return of spontaneous cir- 
culation (ROSC). We found that the positive pre- 
dictive value of detection of ROSC w as only 56'Jf 
(5/9), but the negative predictive value was 959^ 
(20/21 ). We concluded that failure of the Fenem to 
produce cyclic color changes in correctl\ intubated 
patients in cardiac arrest may suggest that ROSC is 
unlikely. Colorimetric end-tidal CO; monitoring 
(Fenem) may be useful to evaluate pulmonary 
blood How during resuscitation.*'"'^'''' '" but more 
work is needed in this area. 





Bicarbonate adniinisiration during CPR may 
affect the usefulness Peico: as an indicator of pul- 
monary blood flow because it will result in an 
increase in PetCO: independent of pulmonary blood 
nov\ . However, to our knowledge no work has 
been done to evaluate this. Although it is premature 
to recommend the routine use of capnography dur- 
ing resuscitation, the use of Petco: as a real-time, 
objective indicator of the effectiveness of resus- 
citation is promising. 

Transcutaneous P02 

Transcutaneous P02 (PtcO^) and Pco: (PtcCO:) are 
measured by placing a small heated electrode 
against the skin surface."" Both canine"^'-" and 
human'-' '-'' studies have shown that PtcO: 
decreases with a decrease in cardiac output and pe- 
ripheral perfusion. It has also been shown that 
PtcCO: 's affected by perfusion; a decrease in per- 
fusion results in an increase in PtcCO:-''^ PtcO: is a 
function of oxygen delixery'"*""'-^ (O^ delivery is 
the product of cardiac output and arterial O^ con- 
tent): in other words. PtcO: tracks PaOz when per- 
fusion is adequate, and PtcO: tracks cardiac output 
when PaO: is adequate. In dogs. PtcO: decreases 
with hemorrhage (Fig. 17) and increases when the 
shed blood is reinfused (Fig. 18)."**'-" In adults 
with normal cardiopulmonary function, the PtcO: 
inde.x (PtcO:/PaO;) is > 0.75. With shock and 



150 300 450 600 

Fig. 17. Changes in transcutaneous P02, mixed-venous 
P02, and cardiac output during active hemorrhage in 
dogs. (Reprinted, with permission, from Reference 118.) 

decreased peripheral pertusion. the Pu-oi index 
decreases, and the magnitude of the decrease is 
determined by the magnitude of the decrease in 


300 450 600 

Fig. 18. Changes in transcutaneous Pqo, mixed-venous 
P02, and cardiac output during fluid infusion in hypo- 
volemic dogs. (Reprinted, with permission, from Refer- 
ence 118.) 

The use of PtcO; monitoring with cardiac arrest 
and resuscitation has been reported. '--'-^^■'-^■'-^ 
During CPR in five patients. Tremper et al'~ 
reported a PtcO: of 0-3 ton\ a cardiac index of 
0.8 ± 0.2 L • nr • min'. a PaO: of 40 ± 1 2 torr. and 
an oxygen delivery of 59 ±41 mL • m- • min '. 
Abraham et al '-''-'■'-" reported a PtcO: of 0-40 torr 
during CPR (Fig. 19). 

Although reports in the early 1980s promoted 
the use of PtcO: as an indicator of the effectiveness 
of CPR. this has not become common practice for 
several reasons. First. PtcO: monitoring is tech- 
nically difficult — particularly during CPR. Second, 
an equilibration period of 10-15 minutes is required 
after placement of the PtcO: electrode, which limits 
its use early in the resuscitation unless the electrode 
was in place prior to the cardiac arrest (which is 

Conjunctival P02 

The conjunctival oxygen monitor uses a minia- 
turized Clark electrode to measure the tissue P02 of 
the palpebral conjunctiva.'-*""* The conjunctival 
eyelid sen.sor (Fig. 20) consists of the Clark elec- 
trode mounted on a hollow acrylic oval conformer. 

RESPIR,'\TORY CARE • JULY '92 Vol 37 No 7 



EOA in trachea. 
CPR in progress 

CPR slopped 
CVP measurement 
PaOj 206 j CPR restaned 
I CPR reslarled | 

* CPR stopped 

I , CPR 
[ stopped 

Time (mm) 

Fig. 19. Changes \n transcutatieous and conjunctival P02 
during resuscitation. (Reprinted, with permission, from 
Reference 126.) 

The sensor tits into the coiiJunctiNal I'ofnix and 
does not eotiie into eontact with the eornea (Fig. 
21). The relationship between conjunctival P02 
(Pcjo:) and Pa02 is the conjunctival index, which is 
calculated by dividing the Pcj02 by the PaO;- In hemo- 
dynamically normal subjects, the conjunctival 
index is > 0.60. However, there is considerable 
intra- and interindividual variability in the rela- 
tionship between Pcjo; and PaO:- '"'''"" The con- 
junctival index also decreases with age.'^^ 


/dT^ "^ 

Fig. 21. Conjunctival eyelid sensor in place in the right 

Several reports have suggested that conjunctnal 
oxygen monitoring is an indicator of cerebral blood 
flow.'''"' '"^ In other words. P^o: decreases with a 
decrease in cerebral blood flow (in spile of a nor- 
mal PaO:). PcjO: has been shown to drop during 
manipulation, clamping, and obstruction of the 
carotid artery.'^""'"" PljO: has also been shown to 
decrease with hyperventilation.'"* ''" In normal sub- 
jects, the reduction in cerebral blood tlow induced 
by hypocapnia is accompanied by a significant 
decrease in the conjuncti\al index (Fig. 22). 

09 - 



30 40 Time 

I (mm) 

ContrsI Mypirirtntilatioo 

Fig. 20. Conjunctival eyelid sensor. 

Fig. 22. Change in conjunctival index with hyper- 
ventilation. (Reprinted, with permission, from Reference 


RFSPIR.ATOR^' C.ARF • Jl'LY '92 Vol .^7 No 7 


The effect of hemorrhage on P^jo: has also been 
reported.''*" '■'■^ In a study of 16 nomiotensive emer- 
gency department patients w ith histories consistent 
with important blood loss, it was found that a con- 
junctival index 0.50 was always associated with a 
blood volume reduced by 15% below predicted 
values (Fig. 23).'""' In dogs, it has been shown that 
















0£ 06 65 

Measured S'ood 


cied Blood 

Fig. 23. Relationship between conjunctival index and 
blood volume. (Reprinted, with permission, from Refer- 
ence 141.) 

the conjunctival index fails to less than 0.50 after 
15 niL/kg hemorrhage (about 18% of blood vol- 
ume), and conjunctival index falls more rapidly and 
at an earlier stage of hemorrhage than does mean 
arterial blood pressure (Fig. 24).'^- However, in 
work done in our laboratory, we found that the con- 
junctival index was not sensitive enough to detect a 
blood loss of 450 mL during the controlled phle- 
botomy of healthy, euvolemic adults.''*' 

Conjunctival monitoring has been used as an 
indicator of cerebral blood flow during resus- 



10 20 30 U 

H*«otrh«q« (alrKq) 

(% of lotal blood volume) 

J I L 




U 30 




a>lu«ioa iBil/Kgl 

I'o ol total blood volume) 

Fig. 24. Conjunctival oxygen and blood pressure during 
hemorrhage and reinfusion of shed blood in dogs. 
(Reprinted, with permission, from Reference 142.) 

citation. '-'^''-''•''*'^'"'" With the onset of cardiac arrest, 
the PgO: drops to nearly zero and increases with 
the return o\' a functional cardiac rhythm (Fig. 25). 
Failure of the conjunctival index to increase during 
resu.scitation is an ominous sign, and is associated 
with an unfavorable outcome (Fig. 26).''*^ ''"* Con- 
junctival monitoring might also provide an earlier 
indicator of cardiac arrest and improvement than 
does transcutaneous monitoring (Fig. 19).'-'''-^ 
However, in a canine study''*'' it was found that 
PcjOi failed to accurately reflect cerebral blood 
flow and oxygen delivery during CPR following 

90 r 




cxi 50 










10 20 30 

Time (min) 


Fig. 25. Conjunctival P02 during changes in cardiac 
rhythm. (Reprinted, with permission, from Reference 




the administration of epinephrine; this is an impor- 
tant limitation of conjuneti\al monitoring during 
resuscitation because epinephrine is ahnost uni- 
versally used during cardiac resuscitation. 


80 O 

y ft 





Fig. 26. Conjunctival P02 (;) and blood pressure (•) in a 
patient after resuscitation: the conjunctival P02 remained 
very low. and the patient did not survive. (Reprinted, with 
permission, from Reference 146.) 

Conjunctival monitors are not commonly used 
during resuscitation for several reasons. First, these 
monitors require electrode preparation and calibra- 
tion that are technically difficult and time-con- 
suming — particularly during cardiac arrest. Second, 
Pej02 i'^ ni^t i' useful indicator of cerebral blood 

flow following the administration of epineph- 
rine.'^" and epinephrine is commonly used during 
cardiac resuscitation. 

Pulse Oximetry 

The use of oximetr\ has bect)me ubiq- 
uitous in critical care. Because pulse oximetry 
relies upon a pulsating vascular bed for proper 
function, its use during CPR has been recom- 
mended.'-''" However, 'noise" and hmb motion dur- 
ing CPR may produce spurious pulse oximeter 
results, and thus pulse oximetry is of very limited 
usefulness during CPR."' 

Blood Gases during Resuscitation 

Arterial blood gases and pH are commonly 
measured during CPR. The results of these meas- 
urements are used to direct therap> related to oxy- 
genation, ventilation, and buffer administration. 
However, recent studies using animal models and 
patients in cardiac arrest have shown that arterial 
and mixed-venous blood-gas values arc marked!) 
different during CPR. In fact, respiratory alkalosis 
can be present in the arterial circulation when res- 



180 - 




60 -I 







H* nmol/L 



-I I- a D- 





P02 torr 

U O- -" 

■fiS I F 




■o o o - 

B- — ll-ffl S g. 

LACTATE, mmol/L 




— ffl-Hi — s — -a 

rii— I— 

_____□ D — - 







Fig. 27. Central-aortic (o). mixed- 
venous (le. pulmonary arterial, Q), 
and great-cardlac-veln (a) hiydrogen 
Ion concentration, Pcq, , P02 , and 
lactate during CPR. (Redrawn, with 
permission, from Reference 157.) 




piratory acidosis is present in the \cnnus circula- 
tion. Presumably, mixed-venous blood-gas values 
and pH reflect tissue levels. This may have impor- 
tant implications both tor therapy and tor outcome. 
Several animal sluiiics have shtnvn that arterial 
blood-gas values tail to reflect acid-base balance 
during CPR. '"''*** All of these studies have shown 
that severe mixed-veni)us hypercarbia and acidosis 
can coexist with simultaneous arterial alkalosis. 
Further, myocardial Pco: (measured in the cardiac 
great vein) is significantly greater than that of 
mixed-venous blood (Fig. 27).'-"'''** A discrepancy 
between the acid-base status of the arterial and 
mixed- venous blood has also been shown during 
the resuscitation of humans.'"''''*' During resus- 
citation, respiratory acidosis typically exists in the 
venous circulation, in spite of respiratory alkakisis 
in the arterial circulation (Fig. 28). It has been sug- 
gested that arterial blood-gas values may be an 
inappropriate guide for acid-base management dur- 
ing CPR.'^'' Arterial blood gases may thus have a 
very limited role in decision making during car- 
diac-arrest management. 


7.3 1- 
6.9 L 

pH, units PCO2. torr 








60 - 









Fig. 28. Arterial (ART) and mixed-venous (PA) pH and 
PCO2 during CPR. (Reprinted, with permission, from Ref- 
erence 159.) 

The venous acidosis that exists during CPR is 
the result of several factors. First, there is an 
increase in CO2 production as the result of the buf- 
fering of lactic acid. Second, there is a low venous 
blood flow, resulting in the accumulation of CO^ in 
the venous circulation. Thus, changes in cardiac 

t)ulput arc rcllcctcd m the mixed-\enous Pco:, 
whereas changes in alveolar ventilation are 
reflected in the arterial Pco: (Fig. 29)."^' 




Fig 29. Effects of alveolar ventilation and cardiac output 
on arterial and mixed-venous Pco2 during CPR. 
(Reprinted, with permission, from Reference 161.) 

Blood gas measurements have been used as 
prognostic indicators of the outcome of the resus- 


In a porcine model, it has been 
shown that a low PaCO: during resuscitation is asso- 
ciated with poor survival; the mean arterial PaC02 
of animals that did not survive the resuscitation 
was < 20 ton."'- In that study, it was also shown 
that arterial Pco:- like end-tidal Pco:, is a function 
of cardiac output and coronary perfusion pressure 
during CPR (Fig. 30). In a retrospective evaluation 
of blood gas values during the resuscitation of 
humans, it was found that survival decreases with 
arterial pH > 7.55, and no patients survived with 
arterial pH > 7.60.'*' Further, there was a higher 



2 20 i 



O 10 


r = 74 
p<0 001 


■^ * P<0001 

T ' 1 ' 1 ' 

15 25 35 

-5 5 15 25 35 -5 5 

Coronary Perfusion Pressure, mmHg 

Fig. 30. Relationship between coronary perfusion pres- 
sure, arterial Pco2 (left), and end-tidal Pco2 (right). 
(Reprinted, with permission, from Reference 163.) 

















rate of surv^ival in patients uith higher bicarbonate 
and PaCO: levels (Fig. 31 ). In a human study during 
resuscitation, it has also been shown that mixed- 
venous P02 is an indicator of survival;"^ in that 
study, all of the nonsurviNors had a mixed-\cnous 
Po: < 31 torr, and nearly ail of the survivors had a 
mixed-venous P02 > 37 torr. 

80j '^'"^'^^ 



£34 35-45 >46 < 20 21-35 i36 

PaCOz, torr HCO3", mEq/L 

Fig. 31. Relationship between survival and PaC02 and 
HCOj" during and 1 hour following CPR. (Reprinted, with 
pernnission, from Reference 163.) 

These data have potentially important implica- 
tions. First, arterial blood-gas and pH values during 
resuscitation are not good indicators of tissue acid- 
base status. Second, a low arterial Pco: and a high 
arterial pH are associated with a poor outcome. 
Finally, because of the respiratory acidosis that 
exists in the venous circulation during resuscitation 
(and for other reasons), the usefulness of bicar- 
bonate therapy during resuscitation has been ques- 

Outcome from Resuscitation 

Resuscitation in the hospital and in the field has 
been conducted for over 30 years. The results of 
these efforts have been reported many times from a 
variety of settings, and the subject has been 
reviewed elsewhere. "'^■'^*' 

Prehospital Resuscitation 

Survival rates from out-of-hospital cardiac arrest 
have recently been reviewed in detail elsewhere.'*^ 
Virtually all of this work has been done in the con- 
text of adult sudden cardiac death. From 1966- 

1988. 74 articles representing 36 communities with 
a minimum of lOO cases each were published in the 
peer-reviewed literature. The overall survival rates 
ranged from 2-44 '/c, with subsets of patients having 
survival rates as high as 879f . 

In an evaluation of presumed adult sudden car- 
diac death in our suburban-rural prehospital system 
(population 38(),()()()).""' we found that I8'7f of 
patients with eariy CPR (less than 4 min) and early 
advanced life support (ALS. less than 10 min) sur- 
vived to hospital discharge, compared with 7% 
with early CPR and late ALS. 69f with late CPR 
and early ALS. and 3% with both occurring late 
(Table 1). Although survival was significantly 
more common in patients with ventricular tTbrilla- 
tion or tachycardia, bradyasystolic arrests were not 
uniformly lethal, even with long CPR and ALS 
times (although sursi\al in this subgroup was rare). 

Table 1 . Cardiac Arrest Admissions and Discharges in Rela- 
tion to CardiopuImonar>- Resuscitation (CPR) and 
.Advanced Life Support (.ALS) Response Times* 


Admissions D 






182 (179^) 

68 (6%) 

heart disease 









63 (8%) 


CPR < 4 min; ALS 

< 10 





CPR < 4 min; .ALS 

> 10 




8 (7%) 

CPR > 4 min; ALS 

< 10 





CPR > 4 min: ALS 

> 10 


390 44 (1 1 9 ) 
>ermission of the publisher 

11 (3%) 

•Data from Reference 

Most reports of prehospital CPR ha\e come 
from mid-size cities with populations less than 1 
million. Survival from prehospital CPR was 
recently reported from a large metropolitan area."" 
In that study (for the year 1987). survival was 
determined for 3,221 cardiac arrest cases. There 
were only 55 survivors (2'7f), with 9\'7c of the 
patients pronounced dead in the emergency depart- 
ment, and an additional 7% dying after hospital 
admission. Results such as these make it clear that 
additional efforts (primarily related to early access 




to the ALS system) are needed to impune sLir\i\al 
related to prehospital cardiac arrest. 

Unfortunately, it is difficult to coinpare survival 
rates from various communities because different 
definitions and reporting formats are used."'*^ In 
December 1990. a consensus conference was ci)n- 
ducted in England to standardize the nomenclature 
for reporting outcome data from prehospital cardiac 
arrest.'^' Thi.s resulted in the "Utstein Style" for 
reporting data from out-of-hospital cardiac arrest 
(Fig. 32). It is too early to e\aluate the effect of this 
format on the reporting t)f data related to presumed 
adult sudden cardiac death. A modified version of 
this reporting format might also be useful to report 
data related to in-hospital resuscitation. 

PODulation Served By EMS 


C«f(j.«c Af<e8(e Con«iclBf»d For CPR 

CPR Not AttsmpteO CPR Ail^mptsd 

NoncirdiBc Etiology Cardiac EtioloQy 

UnwitnesBec] Arreai Byiiander Wiincaaed EMS Wiineased 
Asyalole VF or VT Olher Rhythm 

i i i 

Determine Byetander CPR For Each Sobaet 
Never ROSC Ar^y ROSC 

Expired In pield Or ED Admit To Hoapilal 
Expired In Hoapilal Diacnarged Alive 

Expired IWtthin 24 Hra Ahve At One Year Expired Witlvin One Year 

Fig. 32. "Utstein Style" for reporting data from pre- 
fiospital cardiac arrest. 

In-Hospital Resuscitation 

There have been man> reports of the survival 
rates from in-hospital resuscitation in the past 30 
years (Table 2).'^--"" We reviewed 75 such papers, 
which include 19,190 patients. Due to the variety 
of definitions and terminologies used, it is difficult 
to compare any one study to the others. However, a 
relatively high percentage of patients was resus- 
citated (35%), with an ultimate survival to dis- 
charge of 15%. Although few studies have evalu- 

ated postdischarge outcome (Table 2), it seems that 
manv patients who survive to discharge are still 
alive at least (^ months following discharge. 

Interestingly, survival has changed very little 
over the past 30 years (Fig. 33). Factors that are 

1961-1965 1966-1970 1971-1975 1976-1980 1981-1985 1986-1991 

Fig. 33. Survival from in-hospital resuscitation from 1961 
to 1991. 

most commonly associated with a better survival 
rate are listed in Table 3. Factors such as age and 
the hospital location of the airest do not seem to 
necessarily affect outcome. 

Table 3. Faclors Associated w ith Increased Survival from In- 
Hospital Cardiopuliiionarv Resuscitation 

Non-terminal illness 

Ventricular tachycardia or \entricular fibrillation 
Witnessed arrest and/or short response time 
Resuscitation duration less than 10 tnin 
Well-trained resuscitation team 

Do-Not-Resuscitate Policies 

Since the early 1960s, in-hospital use of CPR 
has become routine. This occurred without any 
mandate from official agencies such as the Joint 
Commission on Accreditation of Healthcare Organ- 
izations. It has been suggested that this reflects the 
widespread belief held by American culture that 
science and technology can delay the aging process 
and death.-'"' Unless a do-not-resuscitate (DNR) 
order has been written, CPR is routinely applied in 
the event of a cardiac arrest. In the past 10 years, 
DNR orders have become more common. -"*'-^-^ This 
.seems consistent with the recognidon that in some 
patients, such as those elderly patients with known 
terminal diseases, CPR attempts are likely to be 
futile. The issue of DNR orders is sensidve and- 



Table 2. Summan of the Literature Reporting Sunival after In-Hospiial Cardiac Arrest 



























Robinson '*- 








































Hollingswonh'* 1969 






































35 (86%) 
42 (33<J) 

144 (48%) 

29 (29%) 

16 (27%) 
41 (37%) 
25 (38%) 
14 (14%) 

36 (35%) 
12 (46%) 

17 (45%) 


100 (50%) 

34 (31%) 

175 (32%) 

48 (40%) 

73 (73%) 

25 (25%) 

21 (27%) 

46 (46%) 

68 (55%) 

95 (59%) 

116 (40%) 

97 (41%) 


36 (35%) 
31 (17%) 

219 (43%) 

314 (42%) 

69 (37%) 

169 (47%) 

125 (41%) 

50 (38%) 

Not specified 

46 (37%) 

115 (33%) 

187 (33%) 

37 (17%) 

66 (23%) 
48 (35%) 
73 (36%) 
48 (26%) 

345 (32.4%) 

520 (45%) 

67 <53%l 

4 (9.5%) 

73 (24%) 

6 (6%) 

8 (14%) 


4 (6%) 
3 (3%) 

5 (5%) 
8 (30%) 

8 (21%) 

40 (16%) 

15 (14%) 

82 (15%) 

20 (17%) 

27 (27%) 

22 (22%) 

9 (12%) 
20 (20%) 

10 (8%) 

38 (23%) 

27 (9%) 
52 (22%) 

30 (8%) 

18 (17%) 

19 (10%) 


28 (9%) 
19 (10%) 

101 (22%) 

44 (15%) 

6 (5%) 

230 (19%) 

26 (17%) 

38 (11%) 

87 (16%) 

31 (15%) 

25 (9%) 

14 (10%) 

28 (15%) 

93 (8.7%) 

277 (24%) 

24 (19%) 

Survival depended upon the nature of the underlying disease, prompt initiation of CPR. 
and the experience of the staff 

65 complications of closed-chest compression in 36 of the patients 

Survival improved by prompt initiation of CPR 

All patients had myocardial infarction; all survivors had ventricular fibrillation rather 
than asystole 

Survival better with ventricular fibrillation, and more common in those < 50 years of age 

5-year experience; many patients alive and well many months following discharge 
Age did not affect success 

Age and sex did not affect outcome; 23/27 (85%) of patients alive an average of 8 mo 
following resuscitation 

No relation between survival and arrest location, time of occurrence, or electrical rhythm 
No correlation between age, sex. underlying precipitating factor, or hospital lo- 
cation and outcome; no patient with asystole sur^ ived 

No survivors in the group of patients considered ""unsalv ageable"; factors associated 
with survival included underlying treatable disease, intensive care unit location. 
Absence of coma and shock, age 40-59 years, and initial arrest tachyarrhythmia 

31/38 (82%) patients alive at 1 year; 22/38 (58%) ali\e 6 years following discharge 
22/26 long-term survivors following discharge (1 lost to follow-up) 

No patient survived with CPR lime greater than 30 min; 49/52 (94%) sunival at 9-42 
mo after arrest 

Patients with ventricular fibrillation who arrested on the medicine ward between 7 ^M 
and 1 1 PM had the best survival rate 

Determinants of success were speed at which CPR was initiated and training of hospital 

Well-trained team affects outcome 

Age did not affect sun'ival; lime from discovery of arrest to initiation of CPR affected 

Well-trained team affects outcome 

10-year experience; 170/230 (74%) alive at 1 year. 136/230 (59%) alive at 2 years, and 
117(51%)anveal 3 years 

64/87 (73.5%) alive at 1 mo; survival associated with middle age. ventricular fibrillation, 
and medical conditions (rather than surgical) 

Age not a factor in survival; poorest results between 1 1 pm and 7 am; best results in 
areas where emergency equipment was readily available 

17/25 (68%) alive at 2-4 years 

Patients with ventricular fibrillation were more likely to survive 

26/28 (93%) alive 2 mo after discharge 

10-year experience; success rate greater in emergency department than on the wards. 

and in patients with cardiac disease, drug overdose, and those undergoing anesthesia 
1 0-year experience 
20/24 (83%) alive at 6 mo; sex and locauon in-hospital did not affect outcome 



Table 2. 

Sun\mary of ihe Lileralure Reporting Sur\ival after In-Hospital Cardiac Arrest. 



Year Patients Survivors Discharged 


















34 (44<;f) 



601 (56^) 



47 (60%) 



34 (34%) 



128 (44%) 






14 (27%) 







84(40 5%) 






117 (48%) 






Not specified 






46 (57%) 






29 (47%) 












77 (44%) 






29 (41%) 






161 (49%) 






28 (23%) 








9 (7%) 






11 (16%) 












34 (24%) 





(54% 1 

25 (28%) 






19 (4%) 






30 (10%) 




Not specified 

5 (8%) 












69 (15%) 




50 (35%) 






38 (46%) 






34 (30%) 



Coronar>' heart disease was associated w ilh the best survival rate, and trauma was as- 
sociated with the lowest sur\ ival rate; surv ival was greater when arrest occurred in 
eniergencN departinenl or ICU than on hospital wards 

Survival more likely with ventricular Ilbrillaiion; age not a factor 

6-year experience: 193/257 (757f ) survival at 1 year. 129/258 (50%) alive al 3 years, and 
52 (207f) alive at 5 years 

Only 2 of the 35 patients who arrested on the general floors survived 

33/41 (80%) of those discharged were still alive at 6 mo; oulcome better with ventricular 
fibrillation and arrests lasting < 15 min: pneumonia, hypotension, renal failure, cancer, 
and a homebound lifestyle before hospitalization were associated with increased mor- 
tality; age and location of arrest did not affect outcome 

All patients were elderly (64-91 yeiU"s); better oulcome with ventricular fibrillation 

CPR more successful in patients with ventricular fibrillation or tachycardia; no relation- 
ship belween success and location in-hospital or lime of day; 21/30 (70%) alive at 6 mo 

Survival was inversely related to length of the arrest; advanced age was not a factor in 

5-year experience in a pediatric hospital 

10/12 (83%) patients ahve al 6 mo. and 7/12 (58%) alive al 36 mo 

Location in-hospital and sex did not affect outcome; outcome better with ventricular fib- 
rillation than asystole 

Success was lowest in emergency depanmeni and greatest in ICU; survival was greater in 
cardiac patients and lower in those with multiple organ failure 

Poorest outcome associated with an initial rhythm of asystole, prolonged resuscitation, 
and arrest in the ICU 

Factors associated with successful outcome included arrest within 24 hours of hospital- 
ization, short duration of CPR. and absence of cardiogenic shock, sepsis, acute renal 
failure, cancer, and pneumonia: factors thai did not affect outcome included age, sex, 
location in-hospiial. time of day. participation by a senior physician or anesthesiologist 

Successful oulcome was associated wiih a witnessed arrest, short duration of resuscita- 
tion, age < 70 years 

All patients had an initial rhythm of asystole; best survival occurred in those who re- 
ceived both norepinephrine and lidocaine; survivors were not significantly different 
from nonsurvivors in terms of age, gender, primary diagnosis, location of arrest, or 
duration of CPR 

Age 40-70 years and arrest in ICU were associated with better oulcome 

10/1 1 (91%) patients discharged were alive and well 1 1 mo post discharge; outcome was 
poorer when arrest lasted more than 30 min, and when arrest occurred between mid- 
night and 8:00 am 

Poorer oulcome in patients aged < 10 years or > 70 years, arrest in the ICU. rhythm or 
asystole or electromechanical dissociation 

29/34 (85%) alive 3 mo after discharge; mortality was greater in those with hypotension, 
azotemia, or age 65 years 

Promptness of initiation of CPR « 10 min), age (< 70 year), lime (other than midnight lo 
8:00 AM), cardiac rhythm (ventricular tachycardia or fibrillation) were associated with 
improved outcome; 14/25 (56%) discharged from hospital alive al 5 years 

All patients 70 years of age; poorest outcomes associated with unwitnessed arrests, asys- 
tole and electromechanical dissociation, resuscitation lasting longer ihan 15 min 

Factors associated with mortality included unwitnessed arrest, need for epinephrine, asys- 
tole of electromechanical dissociation, cardiac rather Ihan respirator)' arrest 

84% of patients had clmical deterioration or new complaints within 8 hours before arrest 

Patients w ith isolated respiratory arrest, ventricular tachycardia or fibrillation, arrest dura- 
tion 10 min were more likely to be resuscitated; 13/15 (87%) discharged were alive 
after 7 mo 

Improved survival in patients arresting in areas other than the emergency department or 
cardiac care unit. CPR duration < 15 min. non-cardiac primar,' diagnosis, non-asystolic 
arrhythmia, less than one intravenous and one drip-administered inotrope. and absence 
of pacemaker insertion and defibrillation 

Patients with electromechanical dissociation, carcmoma. or multiple pathology less likely 
lo be resuscitated; age was not a factor in outcome; 29/32 (9! %) patients discharged 
were alive after 6 mo 

Survival belter with ventricular fibrillation or tachycardia, whendurationof the arrest was 
< 10 min. and wiih a DNR policy in the hospital; age did not affect oulcome 

All arrests in medical ICU; age did not affect outcome; duration of CPR was shorter in 
patients who survived, and patients who survived were less severely ill 




complex; although the issues are important, a thor- 
ough discussion is bcNond the scope of this paper. 


Use of many different types of monitors during 
resuscitation has been described in the literature. 
These monitors differ in their usefulness, technical 
feasibility, initial costs, and long-term costs (Table 
4). There have been many published reports of 
CPR success rates in the hospital and in the pre- 
hospital setting. In spite of considerable advances 
in technology over the past 30 years, survival from 
CPR has changed little over that time. Although 
numerous types of monitoring during resuscitation 
are possible, and sometimes useful, the impact of 
expensive technology on ultimate outcome (sur- 
vival) inust be critically evaluated. 

Table 4. Comparison of Factors for Consideration When 
Using Monitors during Resuscitation 














Tidal volume 





Airway pressure 











Colorimetric CO; 






Lighted stylet 






detector device 





Magnetic lube 






Transcutaneous Po: 





Conjunctival P02 





Pulse oximetry 





Arterial blood gases 





Venous blood gases 






We thank Ann Ropp for her help with the preparation of 
the manuscript, the staff of the Philip A Hoover MD Library 
for their help with the literature search, and the York Hospital 
Media Services Department for their production of the illustr- 


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Hess Discussion 

Kacmarek: Has a study looked m 
monitorint; tidal volumes during bag- 
\alve-mask or nioLith-to-mask setups 
during aeiual cardiac arrests? You 
mentioned data dealing u ith the intu- 
bated patients, but hov\ about the 
nonintubated patient? 
Hess: There are none that I know of. 
1 don't think anybody has done that 
work. Tom (Barnes), have you seen 
any work like that in your review of 
the literature? The work that I've 
seen done has been after patients 
have been intubated, and there is not 
even very much of that. There is a 
study by Ornaio el al,' anti I think 
that's about the only one. 

1. Omato Jl'. BrysoM BL. Doiunan PJ. 
Farquharsoii RR, Jaegar C. Measure- 
menl of vcmilalion during cardiopul- 
monary resuscitation. Cril Care Med 
1983; 11:79-82. 

Barnes: Omato et al's paper is the 
only one that reports actually meas- 
ured compliance (and that's really 
dynamic compliance because it 
includes airway resistance). The 
point is that with airway pressures of 
30 cm H:0 and higher, the mask 
begins to lift. If it takes 40 cm H:0 
pressure to ventilate someone who 
may have high impedance with large 
tidal volumes, then it's no wonder 
that the volumes delivered v\ith the 
bag-valve-mask are lower than 600 
mL. You actually are asking the kind 
of question I wanted to ask. Dean 
(Hess). With tidal \olume mon- 
itoring, can a therapist modify his 
technique with the feedback, so that 
he can deliver 600 mL and higher? 
Hess: Well, perhaps so. I guess I 
have a couple of thoughts: The first 
is that maybe it is more important for 
the therapist to be getting the patient 
intubated than to be trying to do a 
good job of bag-valve-mask ventila- 
tion. The other thing is that 1 think 
that tidal volume moniloring is most 

useful in training persons to use the 
bag-\al\e-mask lechmque. 1 think 
that a spirometer is used probably 
only infrequently when therapists 
and other .AC'L.S pro\ iders arc taught 
\entilalion techniques — so thai ihey 
can begin to learn what volumes ihey 
can or cannot deli\er with the tech- 
niques a\ailablc. 

Barnes: 1 agree with you. and I think 
if we could use the gastric model (so 
that we could show ihcm ilic aniounl 
of air going lo the stomach \ersus 
the amount going to the lung ana- 
log), we'd really make an impact 
related to the importance of longer 
inspiratory times and lower peak 
flows and pressures. 
Hess: I can tell you that therapists 
have a difficult time judgmg the \ol- 
ume that they're delivering. When 
we did our study back in the early 
1980s that we talked about earlier 
this morning.' we had some ther- 
apists who thought that they were 
delivering very good volumes. When 
we showed them the volumes that 
they were actually delivering, they 
said. "That can't be right. There must 
be something wrong with the spi- 
rometer." So. they dragged in the cal- 
ibration syringe and squirted gas 
through the spirometer, and the spi- 
rometer was just t"ine. So. they said. 
"Well, let me go again." So. we let 
them go again, and they swore that 
they were delivering good \(ilumes, 
but they weren't. You can't tell by 
looking at chest movement and so 

I. Hess D. Baraii C. Venlilatory vol- 
umes using mouth-lo-moulh. moulh- 
to-mask. and bag-vahe-mask tech- 
niques. Am J Hmerg Med 1985;.3: 

Reines: I'm getting depressed lis- 
tening tt)day. We always teach peo- 
ple to bag-mask and preoxygenate, 
e\en in a code situation, before intu- 
bating. Is there any evidence that 
we're doing anything with that, other 

than wasting time? Listening to you 
and Tom (Barnes) loda\, I'm won- 
dering if we shouldn't just, say, slam 
a lube in and forget preoxygenation 
and all that. What do you think .' 
Hess: That's an excellent question. I 
guess I'm going to skirt it by defer- 
ring to the anesthesiologists in the 
audience, and 1 guess Charlie (Dur- 
bin) is the only one who is left. It 
would seem to me to make good 
sense to train people to intubate and 
have them concentrate their efforts 
on securing an airway w iih an endo- 
tracheal tube — rather than fiddling 
around with a technique that may be 
less than optimal. That's m\ opinion. 
Durbin: It is not possible to be sure 
that a given person will be capable of 
intubating the trachea under all cir- 
cumstances. The only thing tha( 
saves us and our patients is that we 
recogni/e when the tube is not in the 
trachea. There may be times when 
the best intubator just can't intubate. 
By establishing that intubation is the 
only acceptable method of airway 
management. I think we are limiting 
our options and perhaps "cutting our 
own throats.' We should emphasize 
the need for earlier intubation and by 
personnel other (lian physicians. This 
goal is in process, and we've made 
significant strides lo achieve it. 
Through ihe research that has been 
done by people in this conference, 
the goal of having intubation per- 
formed by other than physicians is 
reasonable and should be attained. 
Hess: Something about bag-valve- 
mask ventilation seems to make 
some therapists kind of 'macho.' 
They are reluctant to admit that they 
are having difficulty getting a mask 
seal, reluctant to say, "Can someone 
help me secure the mask over the 
face so I can squeeze the bag with 
boih hands?" It's like not wanting to 
admit that we just can't get a blood 
gas sample, and we need to have 
somebody else try lo do the 'stick.' 
Kacmarek: I have lo agree with 
Charlie (Durbin) because in too 


RFSPIRATOR^' CARE • JULY '92 Vol .^7 No 7 


many ciicuinsiaiices skilled anes- 
thesiologists are unable to intubate 
for a period of time. I u as as naive as 
everybody else about the inadequacy 
of bag-mask ventilation, but as you 
point out how easy it would be to 
monitor \olume. It realh impressed 
on me the need to look at that more 
carefully. Even though it"s only a 
crude measure of volume delivered, 
it still gives us a "ballpark' figure to 
shoot for. I can't help but believe 
that having \isual feedback would 
improve the ability of the individual 
performing the technique and the 
volume actually delivered. It seems 
to me that what we need is to put 
more emphasis on improving the 
skills of those practitioners who do 
bag-valve-mask ventilation at the 

Hess: I find it very interesting that 
during \olume ventilation in the ICU 
we always monitor volumes; but dur- 
ing emergency ventilations we never 
monitor volumes, and I think that's a 
discrepancy that we should try to 

Mathews: 1 think we also have to 
remember that most cardiac arrests 
in hospitals are not witnessed by 
anesthesiologists, respiratory care 
practitioners, or physicians. You 
have nurses, LPNs, and nurses' aides 
witnessing these arrests and insti- 
tuting ventilation. I'm sure we're not 
going to expect them to become 
experts in intubation. I'm not con- 
vinced that the bag-valve-mask is 
appropriate for them, either. Just 
anecdotally, when I take part in a 
code and get there first, being the 
first person of the "team" to get 
there, nurses are only too willing to 
hand me that bag, because they 
haven't been doing a good job, and 
they know they haven't been doing a 
good job. They're scared of that 
whole situation. I agree with what 
Bob (Kacmarek) says. We need extra 
training. Those people who have the 
initial response responsibilities need 
to have better training in the use of 
those devices. 

Thompson: With all the monitoring. 
I ilidn't really see any reports in 
which the arterial CO: was that high 
during resuscitation. Are there 
reports that it's quite high? We're 
going to monitor volume; we're 
going to monitor pressures; we're 
going to monitor all these things. But 
yet on one of your slides, the ventila- 
tion aspect was very good, but the 
perfusion aspect was very poor. 
Hess: I think we saw some evidence 
of that earlier this morning, with 
some of what Dr Hurst showed and 
some of what Dr Weaver alluded 
to — that Pco: can be elevated during 

Thompson: To what level, though, 
Dean (Hess)? I don't remember. 
Hess: You showed some up into the 
80s, didn't you, Jim (Hurst)? 
Hurst: If you look at the group taken 
as a whole with any airway — oral 
airway, EOA, or ET tube — you 
would assume that ventilation was 
adequate. I think the mean was 
somewhere around 43. but when we 
broke it out and looked at EOAs, for 
example, the mean Pcoi was 88 and 
the mean Pq: was 14 (unpublished 
data). Depending on the type of air- 
way adjunct employed, there can be 
a significant respiratory acidosis. 
Hess: I would add one other thing. 
I've had other people say. We've 
used bag-valve-mask devices for 
years, and whenever we get blood 
gases during a code, the Pco2S are 
always fine. But they don't get the 
blood gas while they're doing bag- 
valve-mask ventilation. They get the 
blood gas after the patient's been 
intubated, and they've been doing 
some other things, and then they get 
the blood gas. I don't know how 
many people, at least in the resuscita- 
tion of adults, draw blood gases very 
often during the bag-valve-mask- 
ventilaiion phase of the resuscitation. 
My experience has been that the 
blood gas comes after the patient has 
been intubated and the airway 

Thompson: The other point I would 
like to make is the use of a manom- 
eter during bag-valve-mask ventila- 
tion. We certainly don't do it during 
pediatric resuscitation. Most of those 
graphs were done after the patient 
was intubated (Fig. 2 of Hess's 
paper). We ignore the pressure dur- 
ing bag-valve-mask ventilation. 
Hess: Are you saying that's good, 
bad, or indifferent? 
Thompson: Well, I am saying that 
the more equipment we put up at the 
airway — certainly in neonatal resus- 
citation — the more confusing it 
really gets. To have someone per- 
severate on the pressure or just watch 
the pressure as opposed to watching 
what's going on in the whole field, 
actually makes it more confusing. 
The time from bag-mask ventilation 
to intubation is a very short period of 
time; so we certainly don't advocate 
using a manometer during bag-valve- 
mask ventilation. An obstructed air- 
way will generate high airway pres- 
sures without any ventilation. 
Hess: That's a good point, and my 
comments during my lecture were 
actually aimed at the intubated 
patient. In fact, in the Goldstein et al 
study, all those patients were intu- 

1. Goldstein B. Catlin EA. Vatere JM, 
Arguin LJ. The role of in-line 
manometers in monitoring peak and 
mean airway pressure during hand- 
regulated ventilation of newborn 
infants. Respir Care 1989;34:23-27. 

Durbin: My concerns are regarding 
conect endotracheal tube placement. 
The use of the light wand is not 
benign. There is one report from the 
University of Virginia of losing a 
light bulb down an endotracheal tube 
from such a device.' The device you 
described to identify correct tube 
placement from the British literature 
works on the principle that when the 
bag is squeezed, refill occurs if the 
tube is placed in the trachea. How 




this gas feels returning from the 
esophagus and stomach is different 
from when it returns from the lung 
and trachea. Anesthesiologists follow 
this sign clinically with anesthesia 
bags and are incorrect from time to 
time. All the reports about this de\ ice 
were from the British literature. ' For 
some reason, hands in Britain are bet- 
ter at feeling this difference than 
those in the U.S. 1 would be skeptical 
of using this de\ice until Txe actu- 
ally seen it used in cardiac arrest. 
These patients may have massively 
distended stomachs, and ventilation 
of the stomach and esophagus can 
feel identical to ventilation of the 

1. Stone DJ. Slirt JA. Kaplan MJ. 
McLean WC. A complication of light- 
wand-guided nasotracheal intubation. 
Anesthesiology 1 984;6 1 :780-78 1 . 

2. Wee. MYK. The oesophageal detector 
device. Anaesthesia 1988:43:27-29. 

3. O'Leary JJ, Pollard BJ. Ryan J. A 
method of detecting oesophageal intu- 
bation or confinning tracheal intuba- 
tion. Anaesth Intensive Care 1988:16: 

Hess: I have to agree that there prob- 
ably is no device (and never will be) 
that is 100<7r sensitive and specific 
under all conditions. Probably what 
we need is a variety of things thai 
can be used. 

Kacmarek: I'd like to ask for some 
closure on your comments about end- 
tidal carbon dioxide (Peico:) mon- 
itoring during cardiac arrest. 1 
couldn't tell from your presentation 
whether you're recommending it or 
not recommending it or you simply 
felt it was an interesting anecdote. 
I've always felt that Pcico: is a very 
misleading value in the unstable, rap- 
idly changing clinical situation, and 1 
was just curious about your opinion. 

based on the information that sou've 

Hess: This is a use of Pcico: that is 
quite different from trying to get 
some handle on what the PaCO: is. 
This is using Peico: to actually look 
at what the status of perfusion, of 
pulmonar) blood flow, is. Per- 
sonally. I think that right now the 
data that have been published by 
Sanders et al.' for example, are inter- 
esting and fascinating, but I can tell 
you that when the CPR buzzer goes 
off at the hospital where I work, ther- 
apists don't go running out to the 
code with a capnograph. I think we 
really need more work to really 
assess the usefulness of Petco; to pre- 
dict patients who are likely to be 
resuscitated; so. I find it interesting, 
but to be quite honest with you. I'm 
not exactly sure that I know what to 
do with it on a day-to-day basis. 

1. Sanders AB. Kem KB. Otto CW. 
Milander MM. Ewy GA. End-tidal 
carbon dioxide monitoring during car- 
diopulmonary resuscitation: a prog- 
nostic indicator for survival. JAMA 

Barnes: I don't want to belabor the 
point, but if we're going to train peo- 
ple to use longer inspiratory times 
with the bag-valve-masks, it's going 
to be diftlcult because there has been 
a tendency to use a high bag-cycle 
rate during resuscitation. A review of 
the literature''' and manufacturers' 
user's manuals shows an over- 
emphasis on maximum cycle rate. A 
rate of 20/min gives you a res- 
piratory cycle of 3 seconds. If you 
allow 1 second for bag refill, you 
start to lose that advantage of a 2- 
second inspiratory time for delivery 
of stroke volume at higher cycle 
rates. Also, if you tell someone that 
they're not delivering 800 mL. the 

will squeeze that bag harder, and 
deliver the gas at a higher inspiratory 
flowrate using a shorter inspiratory 
time. The future may lie with trans- 
port \entilators that are currently 
being used in prehospital work. They 
are small enough to be portable and 
may be more reliable than bag-valve- 
masks. With these ventilators, you 
can regulate inspiratory time, preset 
the volume, and free both hands to 
prevent mask leaks and hyperextend 
the head. Do you agree with using 
transport ventilators for emergency 

1. Garden E. Friedman D. Further stud- 
ies of manually operated self-inflating 
resuscitation bags. Anesth Analg 1977; 

2. ECRI. Manual resuscitators. Health 
Devices 1979:8:133-146. 

3. LeBouf L. 1980 assessment of eight 
adult manual resuscitators. Respir 
Care 1980:25:1136-1142. 

4. Phillips GD. Showronski GA. Manual 
resuscitators and portable ventilators. 
Anaesth Intensive Care 1986:14:306- 

Hess: Sure. 1 think that there has 
been a change of opinion in that 
regard. 1 think 5 years ago all of us 
were taught and taught that >ou 
should not use ventilators during 
resuscitation. 1 thuik that there's now 
some good evidence in the lit- 
erature.' including some that Rich 
(Branson) probably will share with 
us later to indicate that that ma\ not 
be so. 

1 . Johannigman JA. Branson RD. Davis 
K. Hurst JM. Techniques of emer- 
gency ventilation: a model to evaluate 
tidal volume, airway pressure, and 
gasu-ic insufflation. J Trauma 1991; 



The Role of Transesophageal Echocardiography in 

Determining the Mechanism of Fonvard Blood Flow during 

Closed-Chest Cardiopiilmonaiy Resuscitation 

Thomas Porter MD, Joseph P Ornato MD, and JV Nixon MD 


Although closed-chest cardiopulmonary resusci- 
tation (CCCPR) was discovered more than 30 years 
ago.' the mechanism of forward blood flow using 
this technique has not been elucidated. Current 
hypotheses center around two mechanisms: the car- 
diac pump and the thoracic pump. The cardiac 
pump theory suggests that the left ventricle assists 
in forward blood flow during chest compression by 
creating an intracardiac gradient.-'' whereas the 
thoracic pump theory states that forward blood 
flow is achieved by increased intrathoracic pressure 
created by chest compression."'-"' Up until 1960, it 
was generally accepted that blood moved forward 
during resuscitation by direct compression of the 
heart chambers between the sternum and vertebral 
column. Since then, an alternative explanation for 
forward flow has been tested that states that chest 
compression produces a rise in pressure in all intra- 
thoracic blood vessels. This increase in pressure 
causes blood to move forward across all heart 
valves during compression, while retrograde trans- 
mission of pressure and flow to extrathoracic veins 
is prevented by venous valves at the thoracic inlet. 
The pressure difference between extrathoracic 
arteries and veins results in forward blood tTow. 
One major assumption in the thoracic pump theory 
is that the heart is merely a passive conduit during 
resuscitation and that no intracardiac gradients 

The authors are associated with The Medical College of Vir- 
ginia Hospitals, Richmond, Virginia. 

A version of this paper was presented by Dr Porter on October 
4. 1991, during the Respiratory Care Journal Conference on 
Emergency Respiratory Care held in Cancun. Mexico. 

Reprints: Thomas Porter MD. Cardiology Dept. Medical Col- 
lege of Virginia. 1300 E Marshall St. Richmond VA 23298. 

Doppler echocardiography is a portable cardiac 
imaging technique that can be used in emergency 
life support to determine whether the heart plays an 
'active role' in cardiopulmonary resuscitation. 
Transthoracic and. more recenth, transesophageal 
echocardiography have provided further insight 
into the mechanisin of forward blood tlou during 
CCCPR by assessing mitral-valve position and 
transmitral flow, as well as the changes in right and 
left ventricular chamber size during chest compres- 

Transthoracic Echocardiographic Observations 

Initial transthoracic echocardiographic observa- 
tions appeared to support both cardiac and thoracic 
pump theories. Feneley et al" demonstrated that the 
mitral vahe closed with chest compression and 
suggested that an intracardiac ventriculoatrial gra- 
dient occurred, but Werner et al and Rich et al"^ 
demonstrated that the mitral vahe either remained 
open or opened further with chest compression, 
implying that no such gradients existed. Hackl et 
al.'' using simultaneous echocardiography and cor- 
onar)' and carotid blood flow measurements, dem- 
onstrated that coronary and cerebral blood flow 
were greater when the mitral valve closed during 
chest compression than when it did not. They also 
demonstrated that mitral-\alve closure occurred 
with increasing frequency in the same animal when 
compression force was increased. These observa- 
tions demonstrate that echocardiographic deter- 
mination of mitral-valve position alone may iden- 
tify a group of patients in whom more efficient 
cardiopulmonan,' resuscitation is achieved. 

Although transthoracic echocardiography can 
confirm the mitral-\ ah e position during chest com- 
pression, it is technically incapable of detennining 
whether pressure gradients exist across the mitral 
valve (ie, gradients that may be responsible for 




mitral-valve closure). Adequate Doppler and ana- 
tomic assessment of the mitral valve often is not 
obtainable from the transthoracic approach in the 
patient who is endotracheally intubated and receiv- 
ing positive pressure ventilation. Transesophageal 
echocardiography has emerged as an exciting alter- 
native to transthoracic imaging in such circum- 
stances,'""'-' and is well suited to assessing the 
mechanism of mitral-valve function and flow dur- 
ing CCCPR. Observations during CPR 

Initial studies using transesophageal echo- 
cardiography to monitor CPR demonstrated its abil- 
ity to provide high resolution images of the cardiac 
chambers."" Higano et al'^ subsequently dem- 
onstrated that the mitral valve closed during 
CCCPR in humans, whereas Wright'^ showed that 
the valve remained open — results similar to the 
experience with transthoracic imaging. Higano et 
al''' performed transesophageal echocardiography 
in the intensive care unit within 5 minutes of car- 
diac arrest during manual CCCPR and found that 
the right and left ventricular cavities were com- 
pressed and both tricuspid and mitral valves closed. 
However, Wright'^ used biplane transesophageal 
imaging in 4 patients during CPR and showed that 
right, but not left, ventricular compression occurred 
occasionally, but the mitral valve remained open 
during compression. The markedly different find- 
ings may suggest that some patients exhibit pre- 
dominantly thoracic pump mechanisms and others 
exhibit predominantly cardiac pump mechanisms. 

Halperin et al'^ demonstrated with transesoph- 
ageal ultrasound imaging during CPR in 8 dogs 
that lung deflation, not direct cardiac compression, 
may be responsible for mitral-valve closing. In that 
study, intrathoracic pressure was raised without 
sternal compression by inflating the thorax through 
a large-bore cannula while left atrial and ven- 
tricular pressures and mitral-valve position were 
recorded. When the thorax was inflated, left- 
ventricular-to-left-atrial pressure gradients reached 
18 torr and there was color-Doppler evidence of 
mitral regurgitation. The authors proposed that 
mitral-valve closure during compression is 
related to a greater decrease in intra-alveolar artery 
pressure during chest compression when compared 

to left \entricular pressure. Therefore, how deflat- 
able the lung is determines the magnitude of the 
gradient between left atrium and left ventricle. If 
high-pressure ventilation is u.sed, lung compliance 
is decreased, chest compression fails to generate a 
decrease in alveolar vascular pressure, and the 
mitral valve remains open during chest compres- 
sion." On the other hand, if increased intrathoracic 
pressure is created by increasing compression rate 
or force, then greater lung deflation v\ith chest 
compression and a greater frequency of mitral- 
valve closure with chest compression are expected. 
We studied mitral-valve position with trans- 
esophageal echocardiography in 12 patients during 
CPR with a computer-driven mechanical Thumper 
at a compression force of 120 psi and a compres- 
sion rate of 90."* We obser\ed mitral-valve closure 
with chest compression in 8 patients and a per- 
sistent open position in 4 patients. A significantly 
higher peak transmitral flow was observed in the 
group that exhibited mitral-valve closure with chest 
compression (Fig. 1). We have also observed in 
this same group of patients that chest compression 
results in significantly less left ventricular frac- 
tional shortening than right ventricular fractional 
shortening (mean (SD) = 26 (3) 9^ left versus 55 
0)% right; p < 0.05].'" The amount of left ven- 
tricular compression achieved during CPR in 6 of 
the patients (both those who had mitral- valve clo- 
sure with chest compression and those who had a 
persistent open mitral-valve position) has a direct 




i 20 



Mitral Valve Position witti Compression 

Fig. 1. Demonstration of tfie significantly higfier peak 
transmitral flow velocity (p<0.01) dunng cardio- 
pulmonary resuscitation when the mitral valve closes 
with chest compression, as determined by trans- 
esophageal echocardiography (mitral valve closed ■; 
mitral valve open ■). 


RESPIRATORY CARF • .lUI.Y "92 Vol .^7 No 7 


correlation with the patient's anteroposterior chest 
(Jianicter (r = 0.84. p<().()5);-" however, there was 
no correlation between anteroposterior chest diam- 
eter and peak transniitral flow. 

These prchminary data suggest that the amount 
of left ventricular fractional shortening achieved 
with chest compression may have little impact on 
mitral-valve position or flow. Other investigators 
have demonstrated that mitral-valve position and 
forward blood flow during chest compression may 
be more related to compression force. Hackl et al"^ 
ha\e shown with echocardiography that by increas- 
ing compression force in animals from 200 to 500 
newtons, the incidence of mitral-valve closure dur- 
ing chest compression increased from \67( of the 
cycles to 95'7c. The increase in the incidence of 
mitral-valve closure was accompanied by a lOOyc 
increase in common-carotid-artery flow and a 
136% increase in myocardial perfusion pressure. 
These findings are supported by our finding of sig- 
nificantly higher transniitral flow in patients who 
exhibit mitral-\alve closure with chest compres- 
sion. Although Hackl et al" attributed the increased 
myocardial and cerebral flow that they observed 
with increased compression force to the impulse 
theory of CPR,-' they did not measure the amount 
of left ventricular fractional shortening with 
increased compression force. An alternative expla- 
nation for their observations is that the greater com- 
pression force resulted in greater lung deflation and 
a greater decrease in intra-alveolar vascular pres- 
sure relative to left ventricular pressure, which 
would increase the frequency of mitral-valve clo- 
sure. Because the mitral \ alve would be closed dur- 
ing chest compression, a greater volume of blood 
would then enter the systemic circulation. 

In summary, transesophageal echocardiography 
can be utilized to determine the timing and mag- 
nitude of forward and reverse flow in the cardiac 
chambers and. therefore, can assist in determining 
the mechanism of forward blood flow during resus- 
citation and the adequacy of systemic perfusion. 
Although previous transesophageal and transthor- 
acic echocardiographic obser\ations during CPR 
have used mitral-valve position during chest com- 
pression to support both cardiac and thoracic pump 
theories of blood flow, our preliminary anatomic 
and Doppler findings support the concept that 
mitral-valve position and subsequent intracardiac 

and systemic blood flow during CPR may not be a 
function of direct cardiac compression. It is evident 
that more detailed assessment of Doppler flow pal- 
terns in the pulmonary artery, pulmonary vein, 
mitral valve, and ascending aorta are indicated to 
accurately determine the mechanism of right and 
left ventricular flow during CPR before .specific 
recommendations can be made on how to improve 
cerebral and coronary blood flow . 

New CPR Techniques 

Despite uncertainty concerning the actual mech- 
anism of forward blood flow during CPR, several 
new CPR techniques are being evaluated. One is 
vest CPR, which has recently been used in animals 
to create a greater increase in intrathoracic pressure 
during resuscitation. Increased air trapping with 
vest CPR generates higher and more sustained 
intrathoracic pressure that has been shown to 
improve flow to vital organs in animals.-- How- 
ever, vest CPR may simultaneously 
decrease lung compliance due to the air trapping, 
methods of CPR that selectively increase intra- 
thoracic pressure without simultaneously increas- 
ing alveolar pressure (which theoretically could 
occur with high impulse CPR) may be preferred 
methods of improving aortic and coronary per- 
fusion pressure.-' Interpo.sed abdominal counter- 
pulsation during CPR has recently been shown to 
improve the clinical outcome of patients expe- 
riencing in-hospital cardiac airest.-^ The improved 
effect of this mechanical treatment during CPR to 
improve forward blood flow can be quantified by 
transesophageal echocardiography at the time of 
the arrest. 

Recommendations and Conclusions 

Transesophageal Doppler echocardiography has 
the ability to detect how new CPR methods influ- 
ence not only mitral-valve position and flow but 
also pulmonary and systemic flow. Biplane trans- 
esophageal imaging-'' increases the number of 
imaging planes and has the potential for being used 
to measure aortic flow in response to each of the 
new methods of CPR. When available, trans- 
esophageal echocardiographic imaging should be 
combined with pulmonary and systemic arterial 
hemodynamic monitoring in human subjects during 




CPR to rule out rapidly reversible causes of cardiac- 
arrest, as well as to assist in determining the mag- 
nitude and timing of forward blood flow. Because 
of its ability to quantify flow velocity and chamber 
function, transesophageal echocardiography should 
also be used to quantify the effects of any new CPR 
methods in improving transmitral flow. 


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15. Wright RF. Transesophageal echocardiography during 
cardiopulmonary resuscitation in humans (abstract). Cir- 
culation 1990:82:483. 

16. Halperin HR. Weiss JL, Guerci AD. Chandra N. Tsitlik 
JE. Brower R. et al. Cyclic elevation of intrathoracic 
pressure can close the mitral valve during cardiac arrest 
in dogs. Circulation 1988;78:754-760. 

17. Cohen JM. Chandra N, Alderson PO. van AsWegen A. 
Tsitlik J. Weisfeldt ML. Timing of pulnumary and sys- 
temic blood flow during intermittent high intrathoracic 
pressure cardiopulmonary resuscitation in the dog. Am J 
Cardiol 1982:49:1883-1889. 

1 8. Porter TR. Omato JP. Guard CS. Roy VG. Bums CA. 
Nixon JV. Transesophageal Doppler echocardiography 
to demonstrate the mechanism of blood flow during car- 
diopulmonary resuscitation (abstract). J Am See Echo- 
cardiogr 1991:4:279. 

19. Porter TR, Omato JP. Guard C. Roy V. Nixon JV. Trans- 
esophageal Doppler echocardiography during cardio- 
pulmonary resuscitation in humans (abstract). J .Am Coll 
Cardiol 1991:17;16IA. 

20. Porter TR. Ornato JP. Guard C. Roy V. Nixon JV. The 
relationship of body habitus to left ventricular function 
determined by transesophageal echocardiography during 
closed chest cardiopulmonary resuscitation in humans 
(abstract). Clin Res I99I:39:259A. 

21. Kemstine KH. Tyson GS. Maier GW. Olsen GW. Davis 
JW. Rankin JS. Determinants of direct cardiac compres- 
sion during external cardiac massage in intact dogs 
(abstract). Crit Care Med 1981:10:231. 

22. Halperin HR, Brower R, Weisfeldt ML. Tsitlik JE, Can- 
dra N. Cristiano LM. Fessler H. et al. .Air trapping in the 
lungs during cardiopulmonary resuscitation in dogs: a 
mechanism for generating changes in intrathoracic pres- 
sure. Circ Res 1989:65:946-954. 

23. Swenson RD, Weaver WD, Niskanen R.A. Martin J. 
Dahlberg S. Hemodynamics in humans during ciMuen- 
tional and experimental methods of cardiopulmonary 
resusci-tation. Circulation 1988:78:630-639. 

24. Sack JB. Kesselbrenner MB. Bregman D. Survival from 
in-hospital cardiac arrest with interposed abdominal 
counterpuNation during cardiopulmonary resuscitation. 
JA.MA 1992;267:379-.385. 

25. Seward JB, Khandheria BK, Edwards WD, Oh JK, Free- 
man WK. Tajik J. Biplanar transesophageal echo- 
cardiography: anatomic correlations, image orientation, 
and clinical applications. Mayo Clin Proc 1990:65; 




Porter Discussion 

Weaver: What's your opinion on 
emergency arteriovenous extracor- 
poreal circulation? Paramedics or 
physicians might ride on ambulances, 
so that they could insert percutaneous 
catheters into the groin, and get 
patients on bypass quickly — recog- 
nizing the limitations of CPR. 
Porter: Well, clearly, that has been 
used in animal models, and it"s been 
used in certain other high-risk situa- 
tions in which a patient's cardiac 
resene was minimal, like high-risk 
angioplasty.' I don't have that data 
a\ailable to me. I don't know 
whether that would be beneficial. 
Some decision would have to be 
made about who really is a candidate 
because you're 'talking very expen- 
sive.' The major point that I want to 
stress is that we're not in any position 
(hopefully, in 5 years we will be) to 
decide on what's a good way to 
improve forward blood flow with 
closed-chest cardiopulmonary resus- 
citation because the investigations 
have not supported one mechanism 
over another. There's good data to 
support both — and it's probably that 
there's some best combination. But. 
how do you say that increased com- 
pression force on the left ventricle 
will help? How do you go about mak- 
ing recommendations like that when 
you haven't clearly delineated how 
you're causing forward blood tlow 
during CPR. That's my main conten- 
tion right now. and I'm hoping with 
the technology a\aiiable to us that 
within 5 years we'll have answered 
that question and then will be able to 
decide whether \ests. CPR, abdom- 
inal binding, or increased compres- 
sion force or rate will help. It has 
very important implications because 
clearly we make a decision about 
whether something will work based 
on what we think the mechanism of 
forward blood flow is. Yet. we can't 
agree on the mechanism of forward 
blood flow. 

1. .Vlyler RK. Stcrtzer SH. Cardio- 
pulmonary support: the risk and 
benefits of assisted coronar>' angio- 
plasty. J Am Coll Cardiol 1990: 

Kacmarek: Based on >our research, 
how do you do cardie)pulmonary 
resuscitation? What methodology do 
you recommend for coordinating ven- 
tilation and compression? 
Porter: From the hemodynamic data 
that's come out of Seattle.' I am very 
discouraged about simultaneous ven- 
tilation with chest compression. Dr 
Swenson and his group used high 
fidelity micromanometers in the 
aorta, in the right atrium, and in a few 
patients they looked at esophageal 
pressure as an indirect means of 
measuring the intrathoracic pressure. 
They looked at a wide variety of tech- 
niques, just as we're doing with trans- 
esophageal echocardiography right 
now. They looked at increased com- 
pression force. They looked at what's 
called high impulse CPR. by just 
increasing the compression rate — in 
other words, delivering the whole 
acceleration of the downstroke within 
the first third of the compression. 
They also looked at abdominal bind- 
ing and simultaneous ventilation with 
chest compression. They only thing 
they found that improved the cor- 
onary perfusion gradient (ie. the aor- 
tic diastolic pressure minus right 
atrial pressure) was increasing the 
compression rate to 120. When they 
did the simultaneous ventilation with 
compression, they were able to 
increase the aortic blood flow; but 
they also increased the right atrial 
pressure, and they didn't really affect 
aortic diastolic pressure, which 
means that the perfusion gradient 
actually deteriorated during that 
phase of CPR. So. if I were to outline 
what I think is the best mechanism 
for improving CPR. I would go with 
a higher compression rate because I 
belie\e the data from Johns Hopkins" 
that the mitral valve closes (not 

because of direct left \entricular 
compression). I would try to limit 
the number of ventilations because 
we have no trouble ventilating the 
patients. It could be that with the 
current method we're air trapping, 
and we're increasing the actual lung 
volume, making the lung less detlat- 
able. It could be that the more time 
we allow for lung defiation to occur, 
the more we can improve perfusion. 
So. we are looking at projects that 
will look at both ends of that spec- 
trum, decreasing ventilation to com- 
pression ratios of 7:1, as opposed to 
5:1, and also looking at more fre- 
quent ventilations. My hypothesis is 
that the more defiatable we make the 
lung, and the more compliant we 
make the lung, the better aortic 
blood flow we will achieve. I think 
that's a key thing to look into in the 
next couple of years. What's excit- 
ing to me is that we have the tech- 
nology to look at aortic blood flow 
with the biplane transesophageal 

1. Swenson RD. Weaver WD. Niskanen 
RA. Martin J. Dahlberg S. Hemo- 
dynamics in humans during conven- 
tional and experimental methods of 
cardiopulmonary' resuscitation. Cir- 
culation 1988:78:630-639. 

2. Halperin HR. Weiss JL. Guerci AD, 
Chandra N, Tsitlik JE, Brower R, et 
al. Cyclic elevation of intrathoracic 
pressure can close the mitral valve 
during cardiac arrest in dogs. Circula- 
tion 1988:78:754-760. 

Kacmarek: Just a clarification on a 
lower ventilatory rate. How slow? 
Porter: I would say more than 5:1, 
maybe a ratio of 7:1: in other words 
maybe 8 to 9 breaths per minute but 
giving a large volume. As you saw, 
we used a peak inspiratory pressure 
of 45 cm H:0. So, we're using a 
very high pressure system. I'm con- 
vinced from the data that I think you 
or Dean Hess shared that we need to 
measure that volume, to see how 
that varies from patient to patient. 




Maybe that's one of the explanations 
for why the mitral-valve position \ ar- 
ias. I suspect that the key is in deter- 
mining what's going on in the pul- 
monary circulation. Pulmonary 
compliance will be a major deter- 
mining factor as to what is going on 
at the mitral valve with chest com- 
pression, and. therefore, how much 
flow we get to the cerebral circula- 

Fanta: .About your protocol with the 
Thumper — do you viu-y the compres- 
sion force of the Thumper according 
to body habitus and/or patient age, 
factors that might affect the com- 
pressibility of the chest wall? 
Porter: We go with the standard 
compression force of 120 pounds. 
We have not varied that because we 
haven't seen much chest trauma 

occurring from the Thumper. We 
measure the amount of sternal dis- 
placement that occurs with each chest 
compression and record that. Usually, 
Its in the 2-inch range. I haven't 
looked at this data that closely. The 
degree of sternal compression doesn't 
seem to vary that much from patient 
to patient as I thought it would. 
Fanta: Your data pointed out that the 
one predictive factor was antero- 
posterior (AP) diameter and that you 
might compensate by increasing ster- 
nal compression force in the patients 
with a large AP diameter. 
Porter: That's the point. AP diam- 
eter correlated very closely with 
amount of left ventricular fractional 
shortening we obser\ed, but it does 
not appear to be correlating v\ith the 
amount of transmitral flow that we 

get. In other words, the bigger the 
patient is. the less we'll probably see 
the left ventricle change in size, but 
that doesn't seem to have any influ- 
ence on how much flow we're get- 
ting, implying a different mech- 
anism for getting flow across the 
mitral valve. We initially said. 
"Maybe we can look at the patient 
when he reaches the emergency 
department, get an index of the AP 
diameter, and determine how much 
force we need to gi\e because that 
correlates very well with the amount 
of left ventricular fractional short- 
ening we achie\e." Unfortunately, it 
doesn't seem to correlate with the 
flow, and therefore we couldn't use 
a patient's chest diameter to deter- 
mine what magnitude of flow we 
were achieving. 



Intrahospital Transport of Critically 111, 
Mechanically Ventilated Patients 

Richard D Branson RRT 


While air- and ground-ambulance transport gar- 
ner much attention, transport of the critically ill 
patient within the hospital is equally challenging 
and more frequently performed. Intrahospital trans- 
port occurs in numerous locations with a wide 
variety of patients. This includes to and from the 
operating theater, from the emergency department 
to the intensive care unit (ICU). and from the ICU 
to diagnostic testing and hack again. 

In this paper I examine the need for intrahospital 
transport and discuss the preparation, monitoring, 
equipment needs, ventilatory-support systems, and 
complications of transport. A detailed list and 
description of currently available transport ven- 
tilators are provided. 

Why Transport? 

Critically ill patients in the ICU frequently 
require diagnostic testing or therapeutic procedures 
that cannot be performed at bedside. These include 
computed tomography (CT) scans, angiography, 
and magnetic resonance imaging (MRI). When 

Mr Branson is Clinical Instructor. Department of Surger>. 
Division of Trauma/Critical Care. University of Cincinnati 
College of Medicine, University Hospital Medical Center. Cin- 
cinnati, Ohio. 

A version of this paper was presented by Mr Branson on Octo- 
ber 4, 1991. during the Respiratory Care Journal Confer- 
ence on Emergency Respiratory Care held in Cancun. Mexico. 

Mr Branson has a financial interest in the Uni-Vent 750 Ven- 
tilator, manufactured by Impact Medical Corporation. 

Reprints; Richard D Branson RRT. Dept of Surgery. Uni- 
versity of Cincinnati Medical Center. 231 Belhesda Ave. Cin- 
cinnati OH 45267-0550. 

transportation is deemed necessary, every effort 
should be made to "take the ICU with the patient." 
This includes taking the appropriate personnel and 
providing for ventilation, care, and monitoring sim- 
ilar to that provided in the ICU. 


Assuring a safe and uneventful transport begins 
long before any movement actually occurs. In elec- 
tive situations, patience is the operative word. Time 
taken prior to transport to stabilize hemodynamics, 
oxygenation, and ventilation is well spent. Electro- 
lyte abnormalities should be corrected and the nec- 
essary invasive monitoring devices (arterial line, 
pulmonar)' artery catheter, intracranial pressure 
monitor) placed and secured. 

While a special transport team is deemed nec- 
essary for interhospital, intrahospital 
transport can best be accomplished by personnel 
familiar with the patient. The type and number of 
personnel should be commensurate with the degree 
of support required and the severity of patient ill- 
ness.' Our ICU guidelines require that a physician, 
respiratory care practitioner (RCP), and nurse 
attend the transport of any mechanically ventilated 
patient. We also find it useful in many instances to 
enlist orientees and students to assist in physically 
moving the patient and equipment to and from the 
destination. Smith et al- have published guidelines 
(Table 1 ) for accompanying staff, based loosely 
upon the Therapeutic Intervention Scoring System 
(TISS)."* This system allows for as few as two 
attendants (one nurse and one transporter) for trans- 
porting stable patients and up to three attendants 
(one physician, one RCP, and one nurse) for crit- 
ically ill patients. These guidelines were developed 
at a teaching hospital and therefore may not apply 
to community hospitals where physicians are not as 




Table 1 . Staff Who Must Accompany and Remain with Patients Who Must Leave the ICU for Tests* 

Purpose: In recognizing the need to observe closely ICU patients during periods of time when the patient must be outside the ICU for 
studies or procedures, the following guidelines are established. 

Type of Patient 

Stable patient with onh an I.V. line 

Stable patient with arterial line 

Patient on \ entilator 

Patient with pulmonary artery catheter or any vasoactive drips 

Patient w ith arterial line, ventilator, and pulmonary artery catheter 

Any unstable patient 

Staff Who Must Acconipanv and Remain with the 
Patient until Return to ICUt 

Staff to be determined by head nurse and ICU director 


RN and RT 
RN and residents 
RN. resident.! and RT 
RN. resident.! and RT 

* Reproduced, with permission, from Reference 2. 

t If appropriate staff cannot be assembled to accompany the patient, the palienl's attending should be contacted. The attending will decide if the patient 

can be transported safely w ithout the specified staff or if the study should be cancelled. The attending will indicate his decision in the form of an order. 
i For patients managed by the medical residents, one of the unit residents must accompany the patient. For patients managed by the surgical resident, a 

resident from the primary surgical ser\ ice must accompan> the patient. A medical student may not substitute for the R.\ or a resident. 

readily available. If the patient's physician is una- 
vailable, an in-house physician should be contacted 
and be available in case of an emergency. Typ- 
ically, the attending physician in the emergency 
room will fill this role. 

Once the personnel are assembled, delineation of 
roles and responsibilities should be established. 
The nurse and/or physician should be in a position 
to observe the electrocardiographic monitor (ECG) 
and reach intravenous (I.V.) pumps to manipulate 
pharmacologic agents. The RCP should be posi- 
tioned at the head of the bed to assure adequate 
control of the airway and provide ventilatory sup- 
port. As always, the team approach is essential for 
a safe, successful transport. 


Equipment for transport must be similar to that 
used in the ICU in terms of performance, yet be 
portable, small, lightweight, and rugged. Of course, 
compromises must be made, and complexity often 
gives way to simplicity for the sake of si/e and relia- 
bility. Items essential for in-hospital transport of 
the mechanically ventilated patient are portable 
monitor, portable ventilator, self-inflating bag, 
laryngoscope, drug box. infusion pump, and stetho- 
scope (Table 2). 

Portable Monitor 

A portable ECG monitor capable of monitoring 
two pressure channels should accompany all 
patients. This allows continuous monitoring of 
heart rate, rhythm, and arterial blood pressure. The 
second pressure channel nia\ be used for patients 
with a pulmonar\' artery catheter or those who need 
intracranial pressure monitoring. The monitor 
should be small and lightweight but provide a dis- 
play large enough and bright enough to be seen 
from iS-lO feet away. This is particularly important 
when the patient is isolated from the caregi\ers, as 
occurs during a CT scan. The monitor should have 
its own rechargeable power supply that continu- 
ously charges while connected to AC power. A typ- 
ical transport takes appro.ximately 80 minutes, -''•■'^ 
of wliich 10-20 minutes is spent in liansit to the 
respective destinations. Based on these figures, a 
portable monitor should be capable of operating at 
least 2 hours without recharging. When possible, 
the monitor should be powered by a permanent AC 
power supply while the patient is stationary. We 
currentl) use a Siemens Sirecust 630 portable mon- 
itor (Fig. 1). The Sirecust 630 weighs 12 kg, and its 
dimensions are 21 cm W x 13 cm H x 10.5 cm L. 
This monitor has two pressure channels. pro\ides a 
continuous display of ECG. heart rate, .systolic, dia- 




Table 2. Essential Ecjuipment tor Transport of the MechaniealK Ventilated Patient 



Portable monitor 

Portable \ entilator or selt'-intlating bag 

Air\\a\ maintenance 
Drug box 

Infusion pumps 

ECG; 2 pressure channels for monitoring arterial blood pressure and pulmonary artery 
pressures or intracranial pressure 

IMV and/or AMV; PEEP; PEEP compensation of the demand valve; disconnect 
alarm; manual breath control; separate frequency and tidal volume controls, low gas 

Laryngoscope, endotracheal tubes 6- to y-mm ID, curved and straight laryngoscope 
blades, oral and nasal airways, stylet, Magill forceps, batteries, tape 

Epinephrine, sodium bicarbonate, atropine, calcium chloride. I.V. fluids (DsW and 
lactated Ringer's solution), I.V. tubing, other drugs currently being delivered in the 
ICU (sedatives, paralytic agents, vasoactive agents, and anti-arrhythmics) 

Must operate reliably from an internal battery. 

stolic, and mean blood pressuie.s, can display tem- 
perature, and is also capable of operating a non- 
invasive blood pressure (NIBP) cuff. High and low 
alarms for each monitored parameter can be set, 
silenced, or disabled by the operator. 

Monitoring blood pressure noninvasi\ely during 
transport is essential when the patient lacks arterial 
access. However, recent work by Runcie et al dem- 
onstrates that NIBP underestimates systolic blood 
pressure by 13-219f and overestimates diastolic 
pressure by 5-27% during transport when com- 
pared to direct measurement." These inaccuracies 
have been ascribed to movement of the patient or 

Fig. 1 . Sirecust 630 portable monitor. 

simply the difference between the two techniques 
in a heterogenous group of critically ill patients.^-^ 
In any event, trends are to be followed. Whenever 
direct measurement of arterial blood pressure is 
precluded, intermittent manual oscillometric values 
should be ascertained. 


Ventilatory support during transport has been 
the subject of several recent investigations.'''" 
Hurst et al,' Gervais et al,'" and Braman et al" 
have all demonstrated that inanual ventilation with 
a self-inflating bag during transport can lead to 
unintentional respiratory alkalosis. In each of these 
studies, episodic hypotension and cardiac dys- 
rhythmias were as.sociated with this rapid change in 
acid-base status. Results from our study'' are shown 
in Table 3. Gervais and colleagues demonstrated 
that hyperventilation could be avoided if tidal vol- 
ume (Vt) and minute ventilation (Vfe) were mon- 
itored with a portable spirometer.'" All three stud- 
ies suggest that use of a transport ventilator avoids 
unintentional hyperventilation and is superior to 
manual ventilation during 

Weg and Haas recently reported that manual 
ventilation of critically ill patients during transpoil 
can be accomplished without detriment.'- They 
cornpared blood gas and pH values while patients 




Table 3. Changes in Blood Gas and Hemodynamic Parameters during Transport* 


After Manual 


After Transpon 






7.39 (0.03) 

7.51 (0.02)t 

7.41 (0.02) 

7.40 (0.03) 

Paco: (torr) 


30 (3)t 



P02 (torr) 





Heart rate/min 





Systolic BPimm Hg) 





Diastolic BP tmm Hg) 





* All values are mean (SD). Average transport time = 9 (3) minutes during manual ventilation and 8(3) minutes during transport ventilation. Reproduced 

with pennission. from Reference 9. 
t p < 0.05 compared to conventional ventilation. 

were being manually ventilated to values obtained 
while patient.s were mechanically ventilated in the 
ICU. In their group of 20 patients, only 1 patient 
was found to have acute respiratory alkalosis (pH 
increased 0.13 units and PaCO: fell 9 torr). How- 
ever, in their report, there was a tendency for pH to 
rise and PaCO: to fall during periods of manual ven- 
tilation. They also had 1 patient who had a rise in 
PaC02 of 13 torr. Weg and Haas concluded that use 
of a transport ventilator is unnecessary and expen- 

I believe that manual ventilation is acceptable 
when a skilled RCP is available and there are not 
significant periods of time when the practitioner 
cannot reach the self-inflating bag (eg. rounding 
comers, passing through doors, and entering eleva- 
tors). However, the reality of transport cannot guar- 
antee this, and interoperator variability is inev- 
itable.'^ Therefore, we consider use of a transport 
ventilator or a system that allows delivered Vt to 
be measured to be the preferred method of ven- 
tilatory support during transport. 

Characteristics of a Ventilator for 
Intrahospital Transport 

Operational Characteristics 

Ideally, the transport ventilator should be capa- 
ble of operating in both the intermittent mandatory 
ventilation (IMV) and assi.sted mechanical ventila- 
tion (AMV) modes. However, a single mode may 

be acceptable if the majority of patients are man- 
aged in the ICU with that technique. There should 
be separate controls for respiratory frequency (f) 
and tidal volume (Vj), and delivered Vj should be 
within 10% of set Vj regardless of peak inspiratory 
pressure (PIP). A continuously adjustable Fio: is 
generally unnecessary in adults, for whom 100% 
O2 is acceptable. Infants at risk for developing retin- 
opathy of prematurity (ROP) should be ventilated 
with the appropriate Fio:- It should be remembered 
that delivery of a precise Fio; will require an air 
tank and air-oxygen blender, thus increasing the 
cost, complexity, weight, and size of the transport 
system. Alternatively, .some ventilators 
utilize venturi systems that entrain room air to de- 
crease Fio: and prolong oxygen-source life.''*''^ The 
application of positive end-expiratory pressure 
(PEEP)/continuous positive airway pressure 
(CPAP) should be possible, and a demand valve, 
able to compensate for elevated baseline pressures, 
should be available if IMV is used. A basic alarm 
system, consisting of a low-pressure/disconnect 
and high-pressure alarm must also be included. 


Size and weight are chief concerns for transport 
ventilators. A weight less than 5 kg is desirable, 
and the ventilator's dimensions should make it easy 
to mount it on or place it on the bed. Orientation of 
controls should be in a single plane, and inadver- 
tent movement of dials difficult. 




Power Source 

Pneumatically powered and operated ventilators 
ha\e been considered preferable to those requiring 
electronic control.^ The reasoning has suggested that 
if two power sources are required, the likelihood of 
failure is doubled with a device requiring both gas 
and electric (batten.) supplies. As usual, there are 
tradeoffs with each type of ventilator. While pneu- 
matic ventilators require only one power source, they 
often consume gas for operation, depleting the gas 
source more quickly. And while an electronically 
controlled device has the possibility of battery fail- 
ure, these ventilators generally provide more precise 
control of settings, iire less likely to be affected by 
fluctuations in source-gas pressure, and do not con- 
sume as much gas during operation. Both types have 
been used successfully.'""'" 

Gas Consumption 

Under ideal circumstances, all gas leaving the 
oxygen cylinder would be delivered to the patient. 
However, pneumatic and tluidic logic circuits often 
consume gas to control inspiration and expiration. 
In some instances, gas is also consumed by pneu- 
matic components of electronically controlled ven- 
tilators. "" By gas consumption. I mean gas used by 
the ventilator for operating circuits or valves, 
which is released to the atmosphere not delivered 
to the patient. Acceptable levels of gas consump- 
tion are < 5 L/min. 

Assembly and Disassembly 

The ventilator breathing circuit and exhalation 
valve should be simple, and incorrect assembly 
should be impossible. Likewise, gas-inlet and gas- 
outlet fittings should be different so that improper 
connection is prevented. If a patient valve is used 
to direct inspiratory and expiratory flow (such as a 
nonrebreathing valve), it should be easy to clean of 
blood and secretions. 


The number and complexity of safety devices 
are limited by the small size of transport ven- 

tilators. A high-pressure-reiief valve that vents gas 
to the atmosphere at a preselected PIP is essential. 
Activation of the high-pressure limit should be sig- 
naled by a visual or audible alarm to alert the oper- 
ator. An anti-asphyxia valve that allows the patient 
to breathe from ambient air in the event of gas- 
source failure is akso desirable. Battery-powered 
ventilators should be equipped with a "low-battery" 
signal that indicates when 1 hour of power remains. 
Loss of oxygen power to the ventilatt)r should also 
result in an audible or visual alarm. 


Transport ventilators should be built to with- 
stand the harsh treatment given them during move- 
ment. Control knobs should be protected to keep 
them from being broken off or cracked. If the ven- 
tilator is accidentally dropped from the bed, it 
should withstand the shock and continue operating. 
If it fails following impact, it should fail either 
closed (no gas delivery) or open to ambient air (no 
pressure rise). 

Ease of Operation 

A delicate balance between operational flexibil- 
ity and simplicity must be maintained. Most trans- 
port ventilators have controls for Vj and f. Addi- 
tional controls should include mode selection, 
inspiratory time or I:E. alarm settings. PEEP (if 
applicable), and a manual breath control. Sensitiv- 
ity should be preset at a minimum level or be cli- 
nician adjustable. 

Ancillary Equipment for Ventilators 

All ventilators require a self-contained oxygen- 
supply source. Both compressed gas cylinders and 
liquid systems can fulfill this need. Intrahospital 
transport is usually accomplished with an E cyl- 
inder or two E cylinders yoked together. This pro- 
vides 630 L and 1.260 L of gas. respectively. We 
routinely use two E cylinders, and whenever pos- 
sible operate the ventilator from stationary sources 
at the destination. For longer transports, an H cyl- 
inder containing 6.900 L may be required. 
Although the H cylinder provides a substantially 
larger supply of gas, it is 152 cm in height, weighs 




68 kg. and requires an additional member on the 
transport team just to move it. Movement of a cyl- 
inder of this size must be accomplished carefully, 
due to potential dangers should it fall from an 
upright position. 

Liquid oxygen systems can provide 860 cubic 
feet of gaseous oxygen for every cubic foot of liq- 
uid. However, most liquid systems cannot operate 
at 50 psig, which is necessary for proper ventilator 
operation. Additionally, should liquid oxygen be 
spilled, its extremely low temperature may result in 
thermal injury.'"'' 

Humidification is frequently overlooked during 
transport of ventilated patients.''' This is in part due 
to the impracticality of transporting the patient with 
the humidifier used in the ICU. The logistics and 
dangers of transporting an electrically powered, 
position-dependent, water-filled device are exas- 
perating. However, some humidification should be 
used, as delivery of anhydrous medical gases to the 
tracheobronchial tree can cause tissue damage in 
less than 30 minutes.-" A passive humidification 
device, or "artificial nose." may be used. These 
devices collect the patient's own respired heat and 
moisture and return them during the following 
inspiration. Artificial noses are not as efficient as 
heated humidifiers, but are particularly suited for 
use during transport.'' Use of an artificial nose may 
result in a progressive increase in breathing-circuit 
resistance, and the patient should be monitored for 
signs of respiratory distress.-^ Also, premoistening 
an artificial nose is inadvisable. It does not improve 
efficiency and only serves to further increase the 
flow resistance of the device. 

Airway Maintenance Equipment 

Airway management is a primary concern dur- 
ing transport and frequently is the responsibility of 
the RCP. During movement of the patient, the pos- 
sibility of disconnecting or pulling i)ul lubes (eg. 
endotracheal, intravenous) is increased. Therefore, 
mcnement of the patient should be done slowly, 
w iih one member of the team solely responsible for 
maintaining the airway. This member should also 
lead the team in deciding when movement should 
take place so thai movcmenl is coordinated and 
efficient. This is usually accomplished by counting 
down from 5 and coordinating movement on the 

count of 1. While away from the ICU. the transport 
team should carrj- all the necessary supplies for air- 
way management (Table 2). The patient" s endo- 
tracheal tube should be secured. Our practice is to 
use adhesive tape to hold endotracheal lubes in 
place. We have not found it necessary to carry a 
cricothyrotomy tray with the team because in 
extremes it can be quickly brought to the patient by 
surgeons capable of performing the procedure. 

Infusion Pumps 

Continuous delivery of fluids and pharmacologic 
agents should not be interrupted during transport. 
Infusion pumps can be easily attached to I.'V. poles 
and are usualK capable of operating for several 
hours on internal batteries. These devices should 
have alarms to warn of infusion problems and 
should be as small and lightweight as possible. 
When the patient is receiving enteral nutrition, we 
usually elect to discontinue feeding during trans- 

Drug Box 

A drug box with all pharmacologic agents nec- 
essary to treat emergencies should accompany the 
team. Additionally, extra I.V. tluids. l.V. tubing, 
and other drugs currently being administered 
should be a\ ailable. 


The stethoscope is essential equipment for all 
members of the team. Without fancy electronics, it 
can detect the quality and/or presence of breath 
sounds and heart sounds and can assist in the man- 
ual measurement of blood pressure. Generous use 
of the stethoscope is recommended to assure 
patient safety. 

Additional Equipment 

In selected cases, it may be ad\ antageous for the 
transport team to carry a pulse oximeter and a 
defibrillator. Pulse oximetry can detect inadequate 
oxygen saturation prior to the appearance of o\ ert 
clinical signs. " Ho\\e\er. if an Fio; of 1.0 is used, 
the incidence of hypoxemia during transport is 




low.-'* If an oximeter is used, it should have its own 
battery, be relatively insen.sitive to motion, and, 
like all other equipment, be as small and light- 
weight as possible. 

A defibrillator may be necessary when trans- 
ferring patients with known cardiac disease. In 
some cases, the defibrillator may be part of the 
ECG monitor, in which case additional equipment 
is unnecessary. The defibrillator should have its 
own power suppl\ and meet size and weight 

Physiologic EfTects and Risks of Transport 

The detrimental physiologic effects and risks of 
intrahospital transport have been described by sev- 
eral authors. Howe\er, there is difficulty in com- 
paring results, as some reports consider ECG-lead 
disconnection a complication of transport, while 
others consider only physiologic changes. 

Taylor et al described their experience in trans- 
porting 50 patients with acute cardiac disease.-"* All 
patients had continuous ECG monitoring, and a 
defibrillator accompanied every trip. Forty-two of 
50 patients were noted to have arrhythmias during 
transport, and in 22 of these this was considered 
life-threatening, requiring immediate treatment. 
The average length of transport in this survey was 
57 minutes. The authors noted that transport also 
resulted in an increase in heart rate but no con- 
sistent change in blood pressure. No patient died 
during transport. Taylor and colleagues concluded 
that ECG monitoring of these patients was essen- 
tial, and they speculated that patient movement, in 
and of itself, may predispose the patient to arrhyth- 

In 1975, Waddell published results of a pros- 
pective trial of patient transport.-' He studied 55 
patients transported to and from the ICU during a 
5-month period, and reported that "one patient a 
month suffered major cardiorespiratory collapse or 
death as a direct result of movement." In one 
instance, movement resulted in renewed bleeding 
from a pelvic fracture and death. In two cases, 
movement was associated with cardiac arrhythmia 
and hypotension, and in one case airway obstruc- 
tion occurred. In the second part of his study, Wad- 
dell demonstrated that 70 postoperative patients 
could be moved without incident. Waddell went on 

to recommend that critically ill patients should be 
moved only when absolutely necessary and that 
preparation and stabilization of the patient were 
essential to limit adverse effects. 

Ehrenwerth et al retrospectively studied 204 crit- 
ically ill patients transported to the ICU and iden- 
tified only three instances in which the transport 
process resulted in morbidity."'' They concluded 
that critically ill adults could be transported safely. 

Insel et al described the cardiovascular changes 
during transport of patients from the OR to the ICU 
following major surgery.-^ They recorded heart rate 
and blood pressure preoperatively at 30 min, at 15 
min, and immediately prior to transport; and in the 
elevator, on arrival, and 30 minutes after arrival at 
their destination. They demonstrated that cardio- 
vascular instability was common during transport 
and attributed most of the changes to the emer- 
gence from anesthesia. Additionally, they reported 
cases of hypotension, hypertension, and ventricular 
fibrillation prior to or just after arrival at the ICU. 
Insel et al stated that "transport itself has little 
hemodynamic impact." 

Rutherford and Fisher studied 49 patients during 
transport from a medical ICU.-** They classified 
patients into three groups according to level of sup- 
port required: ( 1 ) ECG monitoring only, (2) inva- 
sive hemodynamic monitoring plus ECG, and (3) 
mechanical ventilation and/or pharmacologic car- 
diovascular support plus ECG and invasive mon- 
itoring. They observed a 45% incidence of life- 
threatening complications during transport, includ- 
ing 5 episodes of systolic blood pressure < 80 torr, 
4 episodes of respiratory distress. 3 disconnections 
of central venous lines, and 2 dysrhythmias requir- 
ing pharmacologic intervention and cardioversion. 
Rutherford and Fisher concluded that "transport 
should be kept to an absolute minimum." 

In 1987, separate studies by Braman et al" and 
Gervais et al'- demonstrated the adverse effects of 
unintentional hyperventilation during transport, as 
previously discussed. However, Braman et al also 
reported other complications during transport. In 
two instances, ventilator malfunction was asso- 
ciated with a deterioration in patient condition. One 
event was caused by battery failure and one by dis- 
connection of the oxygen source. Five patients 
demonstrated significant hypotension, one had 
bradycardia and one had premature ventricular con- 




tractions (16/min). In this study, an LP-6 ventilator 
was used lor ventilation during transport, it is 
unclear whether any adverse effects were related to 
the increased work of breathing seen with this ven- 
tilator in the IMV mode as reported by Kacmarek 
et al.-' Braman et al also suggested that "tests be 
kept to a minimum" and that improvements in ven- 
tilatory support "may substantially reduce the risk 
for serious complications." 

Indeck and colleagues prospectively evaluated 
the risk. cost, and benefits of 103 transports to and 
from the ICU.^ They defined complications as a 
change in oxygen saturation > 57c. a change in 
blood pressure of 20 torr for > 5 minutes, a change 
in heart rate of 20 beats/min for > ."S minutes, and a 
change in respiratory frequency > 5 breaths/min for 
> 5 minutes. During transports they recorded 
113 significant physiologic changes. The majority 
of changes occuiTcd in blood pressure (46/113). 
followed by heart rate (24/113). respiratory rate 
( 23/ 1 1 3 1, and oxygen saturation (20/1 1 3 ). Indeck et 
al also documented whether the test being per- 
formed outside the ICU altered patient manage- 
ment. They concluded that in their series. 76% of 
tests resulted in no change in patient treatment. 
And while no patient expired or suffered signif- 
icant morbidity. Indeck et al suggested that "the 
decision to transport must be weighed carefull\ in 
the face of a > 76% chance that the result w ill not 
alter management." 

Smith and colleagues prospectively studied 125 
patients requiring intrahospital transport tor "mis- 
haps" related to transport.- The t\ pe and number of 
mishaps ni this study are shown in Table 4. While a 
majority of these mishaps seem inconsequential 
(ECG-Iead disconnection), the 14% incidence of 
monitor power failure is disturbingly high. This 
study demonstrated that one third of all transports 
are associated with mishaps in various degrees. 
However, no patient died during transport. 

The diverse opinions and proof by the cited 
authors leave questions regarding the safety and 
efficacy of transport. We recently completed a 
prospecti\e cohort study of 100 transports." Using 
the method of Indeck et al.'* we monitored the 
patient during transport, as well as a control patient 
remaining in the ICU with a similar ,\PACHE II 
score. We found the incidence of physiologic com- 
plications and equipment failures to be similar in 

Table 4. Frequency of Type of Mishap* 



ECG-lead disconnection 

Monitor power failure 

Combination of above 

Intravenous line infiltration or disconnection 

Vasoactive drug infusion disconnection 

Pulmonan,' arter>' catheter-related mishaps 

CVP catheter-related mishaps 

Arterial line disconnection 

Ventilator disconnection 








*Reproduced from Reference 2, with permission. 
tAs part of a triple mishap. 
±As part of a combined mishap. 

the two groups (71 vs 64 and 5 vs 4. respectively). 
We also monitored arterial blood gases and found 
no differences during transport compared to ICU 
blood gases. Our study demonstrates that the "mis- 
haps" and "complications" often attributed to trans- 
port are experienced by critically ill patients in the 
ICU as well. This suggests that the nature of the 
patient's illness is more important than the act of 
transport. for Magnetic Resonance Imaging 

Magnetic resonance imaging (MRI) is a rel- 
atively new imaging technique, frequently used to 
identify central nervous system disorders.^" Opera- 
tion of the magnetic resonance imager creates a 
strong magnetic field, which necessitates removal 
of all materials with feiTomagnetic components 
from the room. 

This poses a unique challenge to the transport 
team. Patients requiring mechanical \entilation can 
be manually \enlilated using a manual resusci- 
tator'' or an MRI-compatible ventilator. Both ihe 
Omni-Vent and IC-2.A are currentl> capable of 
being used during MRI. Aluminum E cylinders and 
aluminum regulators are necessary for oxygen 
delivery. Conventional electrocardiographic mon- 
itoring isn't possible without special electrodes and 
nonferromagnetic cables connected to the monitor 
outside the room.'- 


RP:.SPIRAT0R^' care • JULY '92 Vol 37 No 7 


Transport Ventilators 

Manufacturers have developed a varict>' of ven- 
tilators for transport, ranging from simple models 
with a single control to complex models w ith built- 
in compressors. I list here those \entilators specif- 
ically designed for in-hospital transport and those 
whose use is documented in the literature. Prices 
are manufacturers" list prices as of February 1992. 
Those ventilators intended for prehospital care are 
only noted here, although complete descriptions 
can be found elsewhere.'^ Tables 5 and 6 compare 
the ventilators described in this paper. 

Bio-Med IC-2A, $4,500 
(Bio-Med Devices, Stamford CT) 

Classification: The Bio-Med IC-2A (Fig. 2) is a 
flow controller that can be pressure-, time-, or man- 
ually triggered, pressure- or tlow-iimited. and time- 
cycled. It is pneumatically powered and fluidically 
controlled. It does not have an air-oxygen blender. 

Bio-Med IC-2A ventilator 

Control: The IC-2A allows the operator to select 
the mode of ventilation by adjusting two toggle 
switches on the front panel. The following modes 
are available. 

CMV (Toggle position: Cycle/Normal) — Inspiration 
is time-triggered, flow- or pressure-limited, and 

SIMV ( Toggle position: Cycle/SIMV) — Inspiration is 
time- (mandator) breaths) or pressure- (spontaneous 
breaths) triggered. How- or pressure-limited, and 
time-cycled. The gas-delivery system for spontane- 
ous breaths is not truly a demand valve. When the 
ventilator senses a spontaneous breath (circuit pres- 
sure falls below the sensitivity setting), the ventilator 
delivers a breath at the inspiratory time and flow set 
on the ventilator but does not pressurize the exhala- 
tion valve. Thus, the IC-2A cannot control tlowrate 
to maintain the desired baseline pressure. 

CPAP (Toggle position: Cycle/CPAP) — Inspiration 
is pressure-triggered, flow-limited, and time-cycled. 
The cycle/CPAP mode operates identically to SIMV 
except that no mandatory breaths are delivered. In 
the event of apnea, no backup rate is available. 

Manual (Toggle position: Manual/Normal) — This 
combination activates the manual breath control. In 
this mode, inspiration is manually triggered, pres- 
sure- or flow-limited, and manually cycled (inspira- 
tion continues until the push button is released). 
Inspiratory time is adjustable from 0.4 to 2.0 sec- 
onds and expiratory time from 0.5 to 4.0 seconds in 
the CMV mode and up to 45 seconds in the IMV 
mode. This allows respiratory frequency to be 
adjusted from 1 .3 to 66 breaths/min. Inspiratory 
tlowrate is adjustable from 20 to 75 L/min, and 
tidal volume is calculated by the equation 

Vj (mLl = inspiratory lime (s) x inspiratory tlowrate (mL/s). 

Tidal \olume is adjustable from 133 to 2,500 mL. 
Baseline pressure is controlled by the uncalibrated 
PEEP/CPAP dial, which allows baseline pressures 
up to 25 cm H^O. The pressure-limit control allows 
PIP to be limited up to 100 cm H2O. In the event 
that the pressure-limiting valve fails, a non- 
adjustable pressure-relief valve limits pressure to 





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Displays: Airv\ jy pressure is displayed on an aner- 
oid pressure gauge over the range -10 to 120 em 
HiO. Pressure-activated "indicators" alert the oper- 
ator to the type of breath delivered: mandatory 
(cycle indicator) or spontaneous (demand indi- 

Alarms: The \C-2A has no audible or visual 

Comment: The IC-2A is a sophisticated transport 
ventilator, apparently capable of ventilating a 
variety of critically ill patients. However, gas con- 
sumption of the tluidic logic averages 12 L/min, 
which severely stresses gas sources. The "demand" 
system may also be a problem in a patient with a 
large spontaneous minute ventilation. There are no 
reports in the literature concerning use of the IC- 

Bird Space Technologies Mini-TXP, $1,150 
(Percussionaire. Sandpoint ID) 

Classification: The Mini-TXP (Fig. 3) is a flow 
controller that is time-triggered, flow-limited, and 
time-cycled. It is pneumatically powered and con- 
trolled and does not have an air-oxygen blender. 
However, the patient valve consists of a sliding 
venturi that entrains room air during normal opera- 

Fig. 3. Bird Space Technologies Mini-TXP ventilator. 



Control: The Mini-TXP operates in the control 
mode, and there is no mode selection control. 

CMV — Inspiration is time-triggered, now-limited, 
and time-cycled. In between mandatory breaths, the 
patient may inspire ambient air through the venturi 
or from a continuous How of gas provided by an 
optional nebuli/er. A manual breath may be deliv- 
ered by depressing the "Insp"" push button. A man- 
ual breath is manually triggered, flow-limited, and 
manually cycled (inspiration continues at the set 
flowrate until the push button is released). 

Respiratory frequency is controlled by an uncal- 
ibrated dial from 6 to 1 50 breaths/min that also con- 
trols I:E from 1:1 to 1:5. Inspiratory flowrate is con- 
trolled by an uncalibrated dial from 10 to 120 L/ 
min. No control for baseline pressure is available; 
however, end-expiratory pressure may be applied 
by a suitable PEEP/CPAP valve. Peak pressure is 
limited by tlow through the venturi at approx- 
imately 120 cm H2O when inlet pressure is 50 psig. 
Delivered Fio: is a function of driving pressure and 
patient compliance and resistance. As back pressure 
increases, entrainment of ambient air by the venturi 
decreases. Therefore, the F102 fluctuates during a 
breath (lowest F102 at the beginning of inspiration 
and highest Fio: at the end of inspiration), and the 
ventilator may deliver an F102 from 0.45 to 0.60. 

Displays: An optional aneroid pressure gauge is 

Alarms: The Mini-TXP has no audible or visual 


Comment: The Mini-TXP is a simple ventilator 
with a wide range of capability. Because the con- 
trols are uncalibrated. a portable respiromeler 
should be used to set tidal volume. When PEEP is 
added, spontaneous breathing from ambient air is 
equivalent to an end-positive airway pressure 
(EPAP) system, which may increase the work of 
breathing. a venturi is used to deliver 
inspired gases, tidal volume may change as com- 
pliance and resistance change. Despite its relative 
simplicity, the Mini-TXP has been shown to be an 
effective transport ventilator for intrahospital and 
prehospital transport.''-^'' 

Hamilton M.vx, $3,300 
(Hamilton .Medical, Reno NV) 

Classification: The Hamilton MAX (Fig. 4) is a 
pressure- or Hovv -controller that is time-, pressure-, 
or manually triggered, pressure- or tlow-limited, 
and time- or pressure-cycled. It is pneumatically 
and electronically powered and uses both electronic 
and pneumatic control circuits. It does not have an 
integral air-oxygen blender. 

Fig. 4. Hamilton max transport ventilator. 

Control: The MAX allows the operator to select Vj 
and f and also allows a manual breath to be deliv- 
ered. The M.^X operates in the IMV mode. 

IMV — Mandatory breaths are time-triggered, pres- 
sure- or tlow-limited. and time-cycled. .Spontane- 
ous breaths are pneumatically controlled and are 
pressure-triggered, pressure-limited, and pressure- 
cycled. Spontaneous breaths are delivered by a 
pneumatic demand valve with a preset sensitivity 
of -2 cm HoO and a demand flow of up to 145 L/ 
min. If PEEP is added by an external PEEP valve, 
triggering is not compensated for the new baseline 

Respiratory frequency is adjustable from 2 to 30 
breaths/min. and inspiratory time is tlxed at 1.0 
.seconds, resulting in an I:E from 1:1 to 1:29. Vj is 
adjustable from 50 to 1,500 mL (inspiratory flow 
30-90 L/min). PIP can be limited up to 100 cm 
H.O by a control inside the ventilator or by a non- 
adjustable factory preset pressure-relief valve at 
120 cm HjO. Manually triggered breaths are man- 
ually cycled, pressure- or tlow-limited. and man- 
ually cycled. That is. gas is delivered at the set 
tlowrate as long as the button is depressed. 

Displays: Airway pressure is displayed b> an aner- 
oid gauge over the range of -10 to 100 cm H2O. 

Alarms: When less than 30 minutes of battery 
power remain, the low-battery alarm illuminates. If 




battery power is discimnecled, im alarm is acti- 
vated. A pressure switch located proximal to the 
internal pressure regulator causes the oxygen alarm 
to illuminate when gas pressure is disconnected or 
tails below 27 psig. 

Comment: The MAX is intended for both in- 
hospital and prehospital transport. It has been 
shown to be a reliable ventilator for in-hospital 
transport."' Due to electronic control, the MAX has 
no gas consumption, and it accommodates spon- 
taneous breathing via a demand \al\e. In an eval- 
uation of the MAX by our group, published in this 
journal we listed the shortcomings of the MAX as 
(1) no low-pressure alarm, (2) the demand system 
is not PEEP-compensated, and (3) the adjustable 
pressure-limit control is accessible only by remov- 
ing the ventilator's cover."* 

Impact Uni-Vent 750, $4,995 

(Impact Medical Corp, West Caldwell NJ) 

Classification: The Impact Uni-Vent 750 (Fig. 5) 
is a flow- or pressure-controller that is pressure-, 
time-, or manually triggered and time- or pressure- 
cycled. It is pneumatically and electronically pow- 
ered and electronically controlled. The 750 does 
not have an integral blender or compressor. 

Calibrated dials and membrane switches are used 
as the operator interface. The following modes are 
available on the 750. 

Fig. 5. Impact Uni-Vent 750 Ventilator. 

Control: The 750 allows the operator to select the 
mode of ventilation, ventilation frequency, inspira- 
tory time, inspiratory flow, pressure triggering 
(sensitivity), and high- and low-pressure alarms. 

Control iCMVj — During CMV, inspiration is time- 
triggered. How- or pressure-limited, and time- 
cycled. .Spontaneous breathing in the CMV mode 
can occur through the anti-asphyxia valve. 

Assist (AMV) — During AMV, inspiration is either 
time- or pressure-triggered, flow- or pressure-lim- 
ited, and time-cycled. 

SIMV — In SIMV. mandatory breaths are flow- 
controlled, time- or pressure-triggered, flow- or 
pressure-limited, and time-cycled. Spontaneous 
breaths are pressure-controlled, pressure-triggered, 
pressure-limited, and pressure-cycled. The 750 
uses an electronically controlled demand valve. 

Ventilator frequency is adjustable from 1 to 150 
breaths/min, and inspiratory time is adjustable from 
O.I to 3.0 seconds, allowing for an I:E of 1:1 to 
1:59. Inspiratory flow is adjustable up to 100 L/ 
min. providing a Vj of 10 to 3.000 mL. Sensitivity 
is adjustable from -2 to -8 in 2-cm-H20 incre- 
ments. Application of PEEP requires an external 
PEEP valve; and the 750 does allow PEEP com- 
pensation for assisted and spontaneous breaths. 

A sigh can be added to all three modes of ven- 
tilation. When activated, a sigh breath is delivered 
every 7 minutes or 100 breaths at an inspiratory 
time 50% greater than the set inspiratory time 
(limit, 3 seconds). 

If apnea is detected in the AMV or SIMV mode, 
the 750 defaults to a ventilation rate of 12 breath.s/ 
min at the current inspiratory time and inspiratory 
flow settings. 

Displays: The 750 uses a window to display ven- 
tilator and alarm settings as well as airway pres- 
sures monitored by an electronic pressure trans- 
ducer. Whenever a control is manipulated or its 
membrane pad depressed, the value for that var- 
iable is displayed in the window. This includes 
ventilator frequency, inspiratory time, sensitivity, 
and alarm settings. Peak. mean, and end-expiratory 
pressures are also displayed. A dynamic display of 
airway pressure is also provided on a vertical bar 
graph. Additionally, indicator lights illuminate next 

RESPIRATORY CARE • .lULY "92 Vol 37 No 7 



to selected functions (Sigh On/Otf, Power), and the 
inspiration indicator light illuminates during a man- 
ual breath. 

Alarms: The 750 has a comprehensive set of 
alarms for both ventilator and patient variables — 
Low Pressure/Disconnect. High Pressure. Inverse 
I:E. Peep Not Set. Apnea. External Power Low/ 
Fail. Battery Low/Fail. FAL (for software memory 
failure), and '■...■' (for transducer calibralit)n fail- 

Comment: The Uni-Vent 750 is intended for inter- 
and intrahospital transport. It is loo sophisticated 
for prehospital use. The ability of the Uni-Vent 750 
to provide three modes of ventilation, allow PEEP 
compensation of the demand valve, and provide an 
essential alarm package is unique among transport 
ventilators. Our group has demonstrated the effec- 
tiveness of the Uni-Vent 750 during in-hospital 
transport.'" We recommend that sensitivity remain 
set at -2 cm H2O, as we noticed that as sensitivity 
was decreased (-6 or -8 cm H2O). inspiratory 
effort was not detected by the transducer because 
gas was inspired through the anti-asphyxia valve.' 

Aequitron LP-6, $9,475 

(Aequitron Medical, Minneapolis MN) 

Classification: The LP-6 (Fig. 6) is electronically 
powered and controlled and can be time- or pres- 

Fig 6. Aequitron LP-6 ventilator. 

sure-unggered. \i)iunie- or pressure-limited, and time- 
cycled. It has a built-in compressor and normally 
delivers an Fio: of 0.21 (no supplemental oxygen). 
The addition of an oxygen accumulator allows 
delivery of a higher Fio2- but with Imiited pre- 

Control: The LP-6 allows the operator to select 
mode of ventilation, tidal volume, ventilator rate, 
inspiratory time, and breathing effort (sensitivity). 
The following modes of \entilation are available 
on the LP-6. 

Assist/control {AMV} — In the AMV mode, inspira- 
tion is time- or pressure-triggered (ie, patient- 
triggered), volume- or pressure-limited, and time- 

SIMV — During SIMV. spontaneous breaths are 
allowed through the cylinder intake valve from 
ambient air. Mandatory breaths are time- or pres- 
sure-triggered, volume- or pressure-limited, and 
time-cycled. If apnea occurs in the SIMV mode, 
the LP-6 will automatically deliver breaths at a rate 
of 10/min. 

Pressure-limited — In the pressure-limited mode, 
inspiration is time- or pressure-triggered, pressure- 
limited, and time-cycled. In this inode, the LP-6 
operates identically to the AMV mode except that 
the high-pressure-aiarm setting limits PIP. Ven- 
tilator frequency is adjustable from 1 to 38 breaths/ 
min and inspirator}- time from 0.5 to 5.5 seconds. 
Vt is adjustable from 100 to 2.200 mL. PEEP can 
be applied with an external PEEP valve. 

Displays: The LP-6 has an integral manometer cal- 
ibrated over a range of -10 to 100 cm H;0 and 
indicator lights for breathing effort and power sup- 

Alarms: The LP-6 has visual and audible alarnis 
for low pressure/apnea, low power, high pressure, 
setting error, and power switchover. The setting- 
error alarm is activated if inspiratory time exceeds 
expiratory time. If this occurs, the LP-6 not only 
alarms, it also does not deli\er a breath. 

Comment: Originally designed for home care, the 
LP-(i has been used for intrahospital transport." 
One of the advantaaes of such a svstem is that it 


RH.SPIRATORY CARE • }{JL\ "92 Vol 37 No 7 


can pro\ide its i)\\n gas suppl\. Ho\\c\er. its size 
and weight (14.8 leg) are. in my opinion, unaccept- 
able for in-house transport. Additionally, the 
imposed work of breathing in the SIMV mode may 
prove detrimental to the critically ill patient in res- 
piratory failure.-" 

Newport E-lOOi, $5,995 

(Newport Medical, Newport Beach CA) 

Classification: The Newport E-lOOi (Fig. 7) is a 
pressure- or now-controlier that may be pressure-, 
time-, or manually triggered, pressure- or flow- 
limited, and pressure- or time-cycled. The E-lOOi 
has an integral blender and tlowmeter and optional 
battery pack. It is pneumatically and electronically 
powered and electronically controlled. 

Fig. 7. Newport E-IOOi ventilator. 

Control: The E-lOOi allows the operator to select 
Fio:- mode, inspiratory time, inspiratory flow, res- 
piratory rate, sensitivity, and PEEP/CPAP. A man- 
ual breath may also be delivered, and a mechanical 
pressure-relief valve can be set to limit peak pres- 
sure. The following modes are available on the E- 

tinuous nt)\\ provided by an external tlowmeter. 
The \entilator controls baseline pressure (PEEP/ 
CP.-XP) only during spontaneous breathing. 

Spoilt — The spontaneous mode allows the patient 
to breathe from the continuous flow via the circuit 
and reservoir bag. Only baseline pressure is con- 
trolled by the ventilator. 

Tidal volume is set by the desired combination 
of inspiratory time (0.1 to 3.0 seconds) and inspir- 
atory How (0.1 to 1.6 L/seconds), allowing a range 
of 10 to 2,000 mL. Respiratory rate is adjustable 
from 1 to 120 breaths/min and PEEP up to 25 cm 
H2O. The mechanical pressure-relief valve can be 
.set to limit PIP up to 100 cm H2O by adjusting the 
uncalibrated control knob. Continuous flow for 
spontaneous breathing in the SIMV and spontane- 
ous modes has a constant flow of 9 to 12 L/min, 
but may be supplemented by the external flow- 
meter up to 30 L/min. 

Displays: The E-lOOi has an integral aneroid pres- 
sure gauge calibrated over the range -10 to 100 cm 
HoO. Indicator lights signal spontaneously trig- 
gered breaths. 

Alarms: The Newport has audible alarms in the 
event of electrical or pneumatic power failures, 
audible and visual high- and low-pressure alarms, 
and an alarm for reverse 1;E. 

Comments: The Newport E-lOOi is a flexible ven- 
tilator capable of ventilating a wide variety of 
patients. It has the necessary equipment to be used 
effectively during transport (eg, battery pack). 
However, it is large and heavy (6 kg without the 
battery pack and almost 10 kg with the battery 
pack). Additionally, use of continuous flow for 
IMV is inefficient and unacceptable for transport. 
The gas consumption of the E-lOOi is excessive 
and includes gas delivered to the reservoir (as a 
bleed from the blender) at 9 to 12 L/min. 

A/C — In the A/C mode, inspiration is time- or pres- 
sure-triggered (ie, patient-triggered), flow-limited, 
and time-cycled. 

SIMV — In the SIMV mode, mandatory breaths are 
pressure- or time-triggered, tlow-limited. and time- 
cycled. Spontaneous breaths are drawn from con- 

Ohmeda Logic 07 (Ohmeda, Madison WI) 
(no longer marketed, but units are in use) 

Classification: The Ohmeda Logic 07 (Fig. 8) is a 
pressure- or flow-controller that is time-triggered, 
flow- or pressure-limited, and time-cycled. It does 
not have an air-oxygen blender but is capable of 




delivering lOO^^r or 50^^^ source gas by use of a 
venturi mechanism. The Logic 07 is pneumatically 
powered and controlled. 

Fig. 8. Ohmeda Logic 07 transport ventilator. 

Control: The Logic 07 allows the operator to con- 
trol minute volume, ventilator rate. Fio; (10 or 
0.5), and pressure limit. It i)perates only in the con- 
trol mode. 

CMV — Mandatory breaths are time-triggered, pres- 
sure- or tlow-limited. and time-cycled. If the 
patient breathes spontaneously, ambient air may be 
drawn in through the nonrebreathing valve at the 

Tidal volume is selected by choosing the appro- 
priate minute volume (4 to 20 L) and ventilator rate 
(10 to 40 breaths/min). allowing a range of 100 to 
2,000 mL. F102 is selected by a toggle switch, 
which, in the 50% position, activates a venturi, 
entraining ambient air and preserving gas supplies. 
Peak pressure can be limited from 20 to 90 cm H;0 
via an adjustable pressure-relief valve. PEEP may 
be added by placing an appropriate valve on the 
nonrebreathing valve. However, with a PEEP valve 
in place spontaneous breathing occurs through the 
length of the patient tubing via the entrainment port 
of the venturi. 

Displays: The Logic 07 has an aneroid pressure 
gauge calibrated from -20 to 100 cm H^O. 

Alarm.s: When the pressure limit is exceeded, gas 
escaping through the pressure-relief \alve creates 
an audible alarm. 

Comment: The Logic 07 is suitable for inter- and 
intraht)spital use. Its ability to vary Fio; helps pro- 
long gas-source life. Morash et al found that the 
Logic 07 was simple to operate, but also found that 
there was up to a 309f variance in actual rate and 
volume compared to set rate and Nolume."*-^ They 
felt that this variance was clinically unacceptable. 
With a PEEP valve attached, an EPAP system is 
created, which ma> cause an increase in the work 
of breathing intolerable to some patients. 

PneuPAC 2-R or HAR\ , $1,100 

(Ohmeda Emergency Care, Orchard Park NY) 

Classification: The PneuPAC 2-R (Fig. 9) or 
HARV (Hope Automatic Resuscitator Ventilator) 
is a flow- or pressure-controller that is time- 
triggered, flow- or pressure-limited, and time- 
cycled. It is pneumatically powered and controlled 
and has an optional patient valve that allows deliv- 
ery of an Fio: of 1.0 or 0.45. An optional com- 
pressor is also available. ■** 

Fig. 9. PneuPAC Model 2-R (HARV) transport ventilator. 


RESPIRATOR^' CARP. • JULY "92 Vol 37 No 7 


Control: The PneuPAC 2-R allows control of ven- 
tilator rate and volume via a single control. It oper- 
ates only in the control mode. 

CMV — Mandatory breaths are time-triggered, 
flow- or pressure-limited, and time-cycled. Spon- 
taneous breathing from ambient atmosphere can 
occur through the expiratory port of the patient 

Respiratory rate and tidal voluine combinations 
are as follows: 



1. 100 

Inspiratory time varies with settings from 0.5 to 
2.2 seconds, and flow is fixed at 40 L/min. PEEP 
can be provided by a manufacturer-supplied PEEP 
valve. Peak pressure can be limited with non- 
adjustable, replaceable valves provided by the man- 
ufacturer (40, 60, and 80 cm H^O). Fio: can be 
selected at the patient valve (0.45 or 1.0) by acti- 
vating a venturi mechanism. 

Displays: The PneuPAC 2-R has an optional exter- 
nal aneroid pressure gauge that can be mounted on 
the ventilator. 

Alarms: If PIP exceeds the selected pressure limit, 
an audible alarm sounds as gas escapes through the 
pressure-limit \ alve. 

Comment: The PneuPAC 2-R is intended for pre- 
hospital care, but several authors have reported suc- 
cessful in-hospital transport with this device. '^'^-^^^ 
While its size and weight are ideal for transport and 
the ability to change Fio: is desirable, its simplicity 
makes it unsuitable for critically ill patients. If a 
PEEP valve is attached to the expiratory port, spon- 
taneous breathino is not accommodated. 

Stein-Gates Omni- Vent D/MRI, $4,700 
(Stein-Gates, Atchison KS) 

Cla.ssification: The Omni-Vent (Fig. 10) is a flow- 
controller that is time-triggered, How-limited, and 
time-cycled. It does not have an air-oxygen blender 
or compressor. It is pneumatically powered and 

Fig. 10. Stein-Gates Omni-Vent transport ventilator. 

Controls: The Omni-Vent allows operator control 
of inspiratory time-tidal volume and expiratory 
time via uncalibrated controls. An optional flow 
control is available. This ventilator operates only in 
the control mode. 

CMV — Mandatory breaths are time-triggered, 
flow- or pressure-limited (by an optional pressure- 
relief valve), and time-cycled. Spontaneous breath- 
ing cannot be accommodated unless an external, 
continuous gas flow is provided. Inspiratory time is 
adjustable by an uncalibrated dial over the range of 
0.2 to 3.0 seconds and expiratory time 0.2 to 6.0 
seconds, providing a respiratory rate of 1 to 150 
breaths/min. The optional pressure-limiting valve is 
adjustable from 20 to 120 cm H.O. 

Displays: The Omni-Vent has an integral aneroid 
gauge that displays pressure from -10 to 150 cm 

Alarms: The Omni-Vent has no visible or audible 

Comment: The Omni-Vent is a flexible ventilator 
that is difficult to operate due to the uncalibrated 
controls. The controls can be turned 360° continu- 
ously, making it difficult to ascertain their position. 
It can be used in magnetic resonance imaging. The 
facts that spontaneous breathing is not accom- 




modated. there are no alarms, and setup is con- 
fusing, make this ventilator undesirable lor use in a 
critical care environment. 

In Coiulusion 

Choosing a transport ventilator appropriate for 
specific needs requires thai clinicians he aware of 
the operation and limitations of each unit. Few 
comparative evaluations have been published.''' 
McGough et al have compared the ability of trans- 
port ventilators to deliver set tidal volume under 
conditions of changing compliance and resis- 
tance.''' Figure 1 1 depicts the results of this evalua- 
tion, which includes several ventilators discussed 
here. The fall in delivered Vj with some ventilators 
further underscores the need to monitor delivered 
V I with a portable respirometer. 

TMal VohiiiM (mO 

(KIM 3000 MAX Bird IC2A P7 E100I Logk) 7 


□ R-20 c-ao 

i^ R-2 C-«0 

^ R*30 C-100 

Control R>X C-100 

Fig. 1 1 . Comparison of tidal volume delivery by transport 
ventilators with varying compliance and resistance. 
(Reprinted from Reference 14, with permission.) 

Safe intrahospital transport is possible if proper 
planning, personnel, and equipment are used. 'Tak- 
ing the ICU with the patient" and vigilance on the 
part of the staff to identify and remedy complica- 
tions early are also important. 


1. Smith IV. F-lcmniing S. lickos C\.. Wnlleii policy and 
patient transport from the intensive eare unit (letter). 
Crit Care Med 19S7;l.'i:l 162. 

2. .Smith I. Flemming S, Cemaianu A. Mishaps during 
transport from the intensive care unit. Crit Care Med 

3. Keenc AR. Cullen DJ. Therapeutie ijitervention scoring 
system: L'pdaie 19S,^. Crit Care Med 198.^:1 1 : 1-8. 

4. Indeek M. Peterson S. Smith J. Brotman S. Risk, cost 
and benefit of transporting ICU patients for special stud- 
ies. J Trauma 1988:28:102()-l()2.'i. 

5. Hurst JM. Davis K Jr. Johnson DJ. Rranson RD. Camp- 
bell RS. Branson PS. Cost and complications during in- 












hospital transport of critically ill patients: a prospective 
stud) ( abstract ). J Trauma 1 99 1 :3 1 : 1 7 1 7. 
Runcie CJ, Reeve W. Reidy J. Dougall JR. A compari- 
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ically ill. Intensive Care Med 1990:16:317-322. 
Runcie CJ. Reeve WG. Reidy J. Dougall JR. Blood 
pressure measurement during transport. Anaesthesia 

Gallagher TJ. .Melker RJ. Transport of the critically ill/ 
injured patient. In: Civetta JM. Tavlor RW. Kirby RR. 
eds. Critical care. Philadelphia: JB Lippincott. 1988: 

Hurst JM. Davis K. Branson RD. Barrelte RR Compari- 
son of blood gases during transport using two methods 
of ventilatory support. J Trauma 1989:29:1637-1640. 
(iervais HW. Ebede B. Konietzke D, Hennes HS. Dick 
W. Comparison of blood gases of ventilated patients 
during transport. Crit Care Med 1987:15:761-764. 
Braman SS. Dunn S.M. .Amico C, Millman RP. Com- 
plications of inter-hospital transport in critically ill 
patients. Ann Intern Med 1987:107:469-473. 
Weg JG, Haas CF. Safe intra-hospital transport of crit- 
ically ill ventilator dependent paiienis. Chest 1989:96: 

Adams KS. Branson RD. Hurst JM Xanahilities in 
delivered tidal volume and respirators rate during man- 
ual ventilation (abstract). Respir Care 1986:31:986. 
Branson RD. McGough EK. Transport ventilators. In: 
Banner MJ. ed. Problems in critical care: positive pres- 
sure ventilation. Philadelphia: JB Lippincott. 1990:254- 

Park GR, Manara AR. Bodenham AR. Moss CJ. The 
PneuPAC ventilator with new patient valve and air com- 
pressors. Anaesthesia 1989:44:419-424. 
Johannigman J.A. Branson RD. Campbell RS. Hursi JM. 
Laboratory and clinical evaluation of the M A.\ transport 
ventilator. Respir Care 1990:35:952-959. 
Campbell RS, Davis K Jr. Johnson DJ. Hurst JM. 
Laboratory and clinical evaluation of the L'ni-Veni 750 
portable ventilator. Respir Care l992:37:29-.^6. 
Ramage CMH, Kee SS, Bristol A. A new portable oxy- 
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Shelly MP. Park GR. Wan-en RE. Portable lung ven- 
tilators: the potential risk from bacterial colonisation. 
Intensive Care Med 1 986: 1 2:328-33 1 . 
Chalon J. Loevv DAY. Malebranche J. F:tfect of dry 
anesthetic gases on the tracheobronchial epithelium. 
Anesthesiology 1972:37:338-343. 
Branson RD. Hurst JM. Laboratorv evaluation of mois- 
ture output of seven airway heat and moisture exchang- 
ers. Respir Care 1987:32:741-747. 
Ploysongsang Y. Bran.son RD, Rashkin MC. Hursi J.\l. 
Pressure flow characteristics of commonly used heat- 
moislure exchangers. Am Rev Respir Dis 1988:138: 




2i. Adams KS, BrunsDii RD, Huisl JM. MoiuU)ring oxy- 
genation with oximetry during transport. Respir Man- 
agement 1987;Nov/Dec:63-6t). 

24. Taylor JO. Landers CF. Cluiki> JL), Hood WB. Abel- 
mann WH. Monitoring high risk cardiac patients during 
transportation in hospital. Lancet 1970;2:1205-1208. 

25. VVaddell G. Movement of critically ill patients within 
hospital. Br Med J I97.S;2:417-419. 

26. Ehrenvverth J, Sorbo S. Hacker A. Transport of critically 
ill adults. Crit Care Med 1986;14:543-547. 

27. Insel J. Weissman C. Kemper M. Askanazi J. Hyman 
AL Cardiovascular changes during transport of critically 
ill and postoperative patients. Crit Care Med 1986;14: 

28. Rutherford WF, Fisher CJ. Risks associated with in- 
house transportation of the critically ill (abstract). Clin 
Research 1986;,U:4I4. 

29. Kacmarek RM. Stanek KS. McMahon KM. Wilson RS. 
Imposed work of breathing during synchronized inter- 
mittent mandatory ventilation provided by five home 
care ventilators. Respir Care 1990:35:405-414. 

30. Lanska MJ. Roessmann \J. Wiznitzer M. Magnetic res- 
onance imaging in cervical and birth injury. Pediatrics 

31. Taylor WF, Pangburn PD. Pa.schall A. Manual ventila- 
tion during magnetic resonance imaging. Respir Care 
1991 :.36: 1 207- 1 2 10. 

32. Glaser R. Fisher DM. Respirators monitoring lor chil- 
dren undergoing radiation therapy. Anesthesiology 

33. Hurst JM. Davis K, Branson RI). Jnhaiiiiigrnan JA. Ash- 
brock S. .Steele J. Ventilatory support in the field: a 
prospective study (abstract). Crit Care Med I989;17: 

34. Goldman E, McDonald J.S. Peterson SS, Stock MC. 
Transtracheal ventilation with oscillatory pressure for 
complete upper airway obstruction. J Trauma 1988:28: 

35. Morash C. Potash RJ. Kacmarek RM. Arguin L. Per- 
formance evaluation of the Ohmcda Logic 07 transport 
ventilator (abstract). Respir Care 1986:31:937-938. 

36. Adams AP. Henville JD. A new generation of anaes- 
thetic ventilators: the PneuPAC and Penlon AP. Anaes- 
thesia 1977;32:34-40. 

37. McGough EK. Banner MJ. Melker RJ. Variations in 
tidal volume with portable transport ventilators. Respir 
Care 1992:37:233-239. 

Branson Discussion 

Kacmarek: As you're well aware, 
the type of patient who is most dif- 
ficult to deal v\ith on a transport is 
the patient v\ith very high minute 
volumes, high Fio:. and significant 
PEEP levels. With the average 
patient, almost any transport ven- 
tilator will work. In the patient that I 
just described, of the ventilators 
available for transport, which one do 
you believe would perfonn that task 
most efficiently? 

Branson: You're asking me for my 
opinion, which one? 
Kacmarek: Of course. 
Branson: This is a hard question. 
We use the 750, the Uni-Vent 750 
(Impact Medical), to ventilate all the 
patients from the ICU now. We have 
used variations and homemade ver- 
sions of ventilators, using Bird 
equipment, for transport. I think if 
you're talking about something you 
can walk over and pick up off the 
shelf, without a lot of clinical exper- 

tise, then you're either going to have 
to use something like the Impact 
ventilator or perhaps the Hamilton 
MAX, depending on whether the 
patient's spontaneously breathing. 
Weaver: We've looked at most of 
the ventilators on your list, and none 
of them performed under those cir- 
cumstances. I think MarDiene (Jeffs) 
will show you the ventilator that we 
use. Contrary to what you stated, you 
can use a liquid-oxygen system for 
air transport, and I trust she'll talk 
about that because that's how we've 
done it for years. A paper published 
in JAMA in 1978 talked about that.' 
The problem as I perceive it is that 
the available ventilators are limited 
to 30-45 L/min and PEEP is either 
not available or 0-25. When the 
patient needs 25-cm HiO PEEP and 
a minute ventilation of 25 L/min 
against a chest compliance of less 
than 10 niL/cm H:0, and has chest- 
tube leaks that amount to another 5 
L/min, none of these ventilators will 
perform adequately. That's why, at 

least in my opinion, there's a real 
need for manufacturers to develop a 
ventilator that can do those things. 
I'm sure it's just an engineering 
problem. Again, the ventilator we 
use is antiquated by today's stan- 
dards, and, yet, it will ventilate 
patients with those requirements. At 
least at our hospital, a large hospital 
with ARDS refeirals over the past 4 
years from all over the country 
because of a prospective trial, we 
routinely inove patients with those 
requirements throughout the hospital. 
I might also add (because a lot of 
people, medical manufacturers in 
particular. Number 1. don't believe 
such patients exist, and. Number 2, 
believe those kinds of patients die. so 
why bother) that our outcome, our 
survival in those patients, is 47% in a 
prospective trial. So, again, the rea- 
son I'm bringing this out is that 
hopefully this will be published, and 
we'll have a document to give to 
ventilator companies — to perhaps 
push them a bit. 




I Harless KW. Morris AH. Ccngi/ M. 
Holl R. SL-hniidl C"D. Civilian ground 
and air transport of adults with acute 
respiraton,' failure. JAMA I978;24(): 

Branson: rni taiiiiliar uiih the 
paper that uses the liqLiicl-o.xyeen 
system. We have yet to find some- 
thing that's really practical to use in 
the hospital. I' II be interested to see 
what you have. One time we had a 
Linde oxygen unit that was capable 
of doing that: but because of the 
problems with refilling it and acci- 
dental burns from spillage, we went 
back to using nothing but tanks. 
Since we rebuilt our hospital, all the 
places that patients go for diagnostic 
testing have piped-in oxygen, which 
is great. The second thing is. those 
patients. I agree, are a problem, and 
lew of those ventilators can ventilate 
those patients. We have ventilated 
those patients, but. again, we have 
Bird equipment that you can't buy. 
ihal ue put tiigcllier \o \'entilate the 
sickest patients, and that's great for 
you and for inc. but it's not going to 
be something everybody else can 

Weaver: Yes. 1 understand. That's 
basically my plea — that the ven- 
tilator manufacturing companies rec- 
ognize the need. I'm not sine that 
they appreciate the need. Most of the 
companies 1 have talked with think 
that the majority of patients can be 
adequately bagged during transport. 
In my opinion, there's a real need for 
the ventilator manufacturers to get 
into this busuiess. 1 travel acioss the 
coiuitry. and I observe patients who 
need a CT scan or a feeding lube or 
whatever, and Ilicy refuse to move 
those patients. I don't know if that's 
good or bad. but at least it certainly 
is different from what vou've pre- 
sented, and certainly iliffereni from 
the situation in our hospital. 
Hurst: .lust one comment. That 
brings up the point of whether the 
requested study will really alter what 

is being done for the patient from a 
therapeutic standpoint. One of the 
ways in which we've gotten around 
this issue is that the ICL' team is not 
responsible for babysitting the 
patient during transport. What we 
have done is to have the team consist 
of the patient's nurse from the ICU 
and the patient's assigned therapist 
for that day and a member from the 
patient's parent medical team. You 
v\ould he surprised how that has 
reduced the number of requested 
diagnostic studies. 

Reines: For our 64 ICU beds, we 
average 4 transports per day. I've a 
leeling our numbers are pretty much 
like everybody else's — only about 
2.5'"f of them end up show ing some- 
thing. But what yiuir study seems to 
show is that you don't need thai learn 
member. You don't need a doctor. 
\'oLi only need a single nurse, per- 
haps, and somebody else to transport 
them — if the mishaps are really the 
same as you get in the unit. What 
we're finding is that when we're at 
2:1 in the unit — and most of our 
units are now — then taking that res- 
piratory therapist and that nurse 
leaves the unit uncovered. We're try- 
ing to work on whether a transport 
team would be worthwhile. It looks 
like your data show that because not 
very much is happening in a trans- 
port, maybe that wmild be worth- 
while. Want lo comment'.' 
Branson: I'm not sure that not very 
mud) is happening. I'm suggesting 
that what's happening on transport 
also happens in the intensive care 
unit. One ol' the things thai 1 looketl 
at — the most difficult part ot the 
study — was trying t(i determine how 
many times a transport affected the 
nurses or the therapists in the ICL' in 
terms of how statTing changed or 
how manv times somebody else had 
to he called to cover for that person 
while they were gone. It actually 
happens about .30-40% of the time. 
One of the problems in these other 
studies is that they don't consider the 

cost of the people who are gone. 
They only consider the cost of the 
test, and 1 think that makes a differ- 
ence. I di>n't kniiw that an in-hospiial 
transport team is the best idea 
because such a team is not always as 
familiar with the patients as the peo- 
ple who are taking care of them. I'm 
sure that it can be accomplished, but 
you're going to lose something there 
in the translation. 

Thompson: Do you maintain a sep- 
arate ventilator in the MRI unit' 
Branson: ^'ou know, we've had an 
MRI unit for I don't know how many 
years now\ and we've only taken twii 
mechanically ventilated patients 
there. ,Si), no, we don't. In fact, an 
ASA abstract' from Gainesv ille Flor- 
ida, looked at taking ventilators to 
MRI and showed that you can take 
almost any ventilator lo MRI, and 
the ventilator continues to t)perate 
properly, as long as you keep it 
shielded. So. I really did not address 
that problem, but, again, that's an 
abstract. When we did take patients 
[o MRI. we took the Bird ventilator, 
which is totally made out of Lexan 
and has no metal parts, and had no 

1. KIl-im .as. Blanch I'B. Evaluation of 
six ventilators within the MRI envi- 
ronment (abstract). .-Xneslhesiology 

Weaver: MarDiene (.leffs). you may 
know how many mechanically ven- 
iihiici.1 patients we've actually taken 
lo .\1R1. I suspect it's between 20 and 
50. We use the Monaghan 225. and ii 
works quite well. 

Barnes: I think you made a good 
case for the advantages of a transport 
ventilator over bag-valve ventilator. 
\\ c saw earlier how bad that can be 
in emergency ventilation. Are any of 
these transport ventilators applicable 
to use m CPR for emergency ventila- 

Branson: Of the ones that I dis- 
cussed, the PneuPAC and the MAX 




are. What I tried to do was keep 
away from that whole host of pre- 
luispiial-lype \ciuihilors. I tlidii'l (.iis- 
cuss them, hut I ha\e written a eliap- 
ler about them that was ptibiisheii in 
Problems in Critical Care (edited by 
Mike Banner).' In that ehapter. I dis- 
euss those \entilators used for pre- 
liospital eare ineluding the LSP 
.'\ulo\ent and Ini|iact's smaller, sim- 
pler prehospital \entilator. We have 
experienee in prehospital eare using 
both the Bird \entilator and the 
Impact 706. In the last group of 160 
patients on whom we ha\e data 
(LHipublishedl. 90 were \entilaled 

with the Impact 706. Those patients 
had itlentieal blood gases, except for 
belter Po^s. than the patients being 
hand-\enlilated via an endotracheal 

I . Branson RD. McCiough EK. Trans- 
port vcnlilalors. In: Banner MJ. ed. 
F-'mblcnis in ciitical care: positive 
pressure \enlilalioii. Philadelphia: JB 
Lippineotl. l99():2.S4-274. 

Barnes: In your recent study.' you 
showed a lot less gastric insuftlation 
for unintubated patients when you 
were using this type. 

I Johannigman JA. Branson RD. DavLs 
K. IliMsi JM. Techniques of emer- 
gency ventilation: a model to evaluate 
tidal volume, airway pressure, and 
gastric insufllation. J Trauma 1991; 

Branson: My personal opinion, and 
we didn't gel aroiuid to that this 
morning, but I think in emergency 
ventilation, initial management ought 
to be endotracheal intubation. In lieu 
of that, you ought to do mouih-Io- 
mask ventilation with supplemental 
oxygen or venlilator-to-mask ventila- 



Air Medical Transport in 1991 

MarDiene Jeffs BS RCP RRT 

The past 20 years (1972-1991) have seen consid- 
erable development and growth in the use of air- 
craft to transport medical personnel to the locale of 
criticallx ill or injured patients — and to transport 
such patients to tertiary care or trauma centers. The 
development of field triage systems in conjunction 
with major trauma-referral centers has had a pos- 
itive effect on the outcome of patients with critical 
illness or trauma. Rapid transport of these patients 
to designated referral centers by trained personnel 
is an essential step in the achievement of higher 
survival rates.'"' In this paper I briefly recall the 
history of air transport and then describe the state 
of the art of this branch of medicine in 1991 — 
covering the varieties of transports; types of air- 
craft; flight-team makeup, skills, responsibilities, 
and training; technology and equipment; airway 
management; mechanical ventilation and ven- 
tilators; special considerations in the transport of 
infants and children; adverse effects of air travel; 
safety; utilization statistics; professional organiza- 
tions; and benefits and risks for tlight-team per- 

1 illustrate some of the material with examples 
or data from the Life Flight program at LDS Hos- 
pital in Salt Lake City, Utah. Our program uses 
roto-w ing and fixed-wing aircraft, and occasionally 
ground vehicles. We classify our transport patients 
in four categories: trauma, cardiac, medical, and 

Ms Jeffs is Associate Director. RespiratoPi' Care Department, 
and Life Flight Therapist. LDS HospitaL .Salt Lake City. L'tah. 

A version of this paper was presented by Ms Jeffs on October 
4, 1991, during the Respiratory Care Journal Conference on 
Emergency Respiratory Care, held in Cancun. Mexico. 

Reprints: MarDiene Jeffs RRT. Respiratory Care, LDS Hos- 
pital. Salt Lake City UT 84143. 


War often speeds the de\elopment of devices 
and methods, and this has included air medical 
transport. The first airlift of casualties supposedly 
occun^ed during the Franco-Prussian conflict 
(1870), when hot-air balloons were used to evacu- 
ate wounded soldiers."* Flight nursing apparently 
began during World War II, when ( 1943) Brigadier 
General David Grant assigned nurses to duty on 
evacuation planes."" In preparation for this, 39 
nurses were sent to Bowman Field, Kentucky, for 
tlight training that included aeromedical physiol- 
ogy, plane-loading techniques, and field survival. 
One of these flight nurses. Colonel Ethel Scott, 
recorded the difficultx lhe\ had with getting litter 
cases in and out of cargo planes, and the noise that 
interfered with attempts to monitor patients" vital 

A great advance was the use of helicopters for 
air medical transport during the Korean War ( 19.^0- 
1953), which became familiar to viewers of the 
popular TV series MASH (Mobile Army Surgical 
Hospital). In that conflict, helicopters were the 
most practical craft for landing and taking off in 
remote, rough, often hill} terrain (as they are today 
in civil-ian medicine). 

The use of helicopters for medical transport was 
further ad\anccd during the Vietnam War (approx- 
imately 1960-1965). where jungle country added to 
the difficulties of rugged terrain in which fixed- 
wing aircraft could not operate. The use of hel- 
icopters was widely recorded in the news-media 
coverage of that war, and later in mo\ies and 
books. Much was learned from these wartime expe- 
riences, hut some original difficulties such as noise 
and patient loading conliniic to challenge flight 




Varieties of Medical Transport 

The transportation of patients includes the fol- 
lowing situations. (1) A transport team goes to an 
ill or injured patient at the scene of an accident, sta- 
bilizes the patient, and then transports him to a 
treatment facility. (2) A transport team accom- 
panies a patient from one medical facility to 
another, usually for treatment available in the des- 
tination facility that is unavailable in the referring 
facility. (3) The team accompanies such a patient 
back to his original medical facility. 

Roto-Wing vs Fixed-Wing Aircraft 

These transports occur by ambulance on the 
ground, fixed-wing aircraft, or roto-wing aircraft 
(helicopter) (Fig. 1). Many factors enter into the 
decision about what \ehicle should be used.''"'' 
Thomas et al found that transports of greater than 
100 miles most appropriately used fixed- wing air- 
craft, because of the faster air speed, reduced need 
for refueling, greater weather capabilities, lower 
operating costs, and better safety record." Within a 
100-mile range, the roto-wing" s fast response time 
is beneficial, especially where accident-scene assis- 
tance is required. However, interhospital transports 
within a 100-niile radius often employ a local 
emergency medical service (EMS) ambulance, tak- 
ing regular flight-team members and their transport 
equipment on the ambulance. These ground trips 
can be made safely and efficiently. At LDS Hos- 

Fig. 1. Interior ot roto-wing aircraft fitted for transport of 
critically ill patients. 

pital we keep a flight-transport pack ready to be 
used on ground transports. 

The Flight Team 

Team Members 

The personnel .serving as members of flight 
teams vary from institution to institution and in 
various circumstances. Team members may be 
nurses, physicians, respiratory care practitioners 
(RCPs), and paramedics. When a helicopter is 
used, space is at a premium, and the medical flight 
team usually is composed of two persons. These 
may be nurse-nurse, nurse-RCP, physician-RCP, or 
nurse-paramedic. A fixed-wing team may utilize 
three members in any combination of nurse, phy- 
sician, and RCP. Fixed-wing transports of longer 
duration may utilize a four-member team. The mix 
of team members is a subject of controversy, which 
indicates that no one combination will meet the 
needs of every air medical transport program or 
emergency situation. 

The current team mix in LDS Hospital's Life 
Flight program has developed over the years 
through evolution and ongoing critical retrospec- 
tive evaluation. Our fixed-wing program began in 
1974, with the roto-wing program following in 
1978. Over the years, many combinations of team 
members have been evaluated. Our current practice 
of nurse-nurse, nurse-paramedic, nurse-RCP, and 
occasionally physician-nurse-RCP is a result of that 
evaluation and evolution. The nurse-paramedic 
team has proven beneficial when dealing with an 
established emergency medical system. With ded- 
icated individuals from hospital- and EMS-based 
systems, response time is greatly decreased and 
patient outcome is enhanced. 

For roto-wing transports, the team combination 
is well established as nurse-paramedic, nurse- 
nurse, and .sometimes nurse-RCP. The fixed-wing 
program utilizes nurse-nurse or nurse-RCP teams, 
with the control physician determining the per- 
sonnel according to the patient's needs. The control 
physician will usually discuss patient-care require- 
ments with the referring physician and then direct 
dispatch orders to specific team members. RCPs 
are used when the patient has compromised ventila- 
tion or is ventilator-dependent. The limited need 




for physicians on fixed-wing transports is made 
possible, in part, by the enhanced communication 
between the control and referring physicians. Gen- 
erall\. foreseeable problems can be discussed, and 
the proper equipmenl and team composition can be 
assigned. Table 1 shows LDS Hospital's uiili/ation 
of various team members in 1940. 

Tabic I J'atlenis of L'tili/alion ot Various Flight-Team Com- 
binations in 1.2.^6 P-'lights at I.D.S Hospital during 

Team Make-Up 

Kind of Nurse- Nurse- Nurse- Physician 

Transport Nurse Paramedic Therapist Utilization 


(Adult I 



















Command Center 

The moving of patients requires a great deal of 
communication and coordination. Each flight pro- 
gram organizes its communication system accord- 
ing to needs and experience. At LDS Hospital what 
we call our Command Center is a system that 
works well for us and our coinmunity. There is dis- 
patch coverage 24 hours a day. rccei\ ing calls from 
"first responders." which include the highway 
patrol, sheriff, ambulance companies, park ser- 
vices. ho.spitals, and even construction sites or the 
scenes of special events when a prearranged agree- 
ment has been reached. 

Upon receiving such a call, the dispatcher then 
responds according to protocols that have been 
developed by the Flight Ser\ ice's medical and 
technical directors. The appropriate response ma\ 
be to automatically dispatch the helicopter to the 
scene of an accident or to patch a referring phy- 
sician's telephone call through to the Life Flight 
Control Physician on call. 

Once decisions have been made concerning the 
patient's needs and the mode of transportation 
(according to distance, patient age. and medical 
problem), the dispatcher alerts all Flight Service 
team members. If the fixed-wing aircraft is dis- 
patched, ground transport is also ananged between 
the hospitals and airports. Our dispatchers are also 
familiar with aeronautical charts and radio fre- 
quencies so they can assist the pilot when nec- 
essary. All communications through the Command 
Center telephones and radios are recorded for later 


Each team member must be highly trained, pos- 
sessing significant expertise in his or her specialty. 
Responsibilities for proper transport of patients 
vary according to the type of patient, severity of 
patient needs, skill levels and specialties of team 
members, and transport vehicle. 

Team members should be certified in advanced 
cardiac life support (ACLS). pediatric advanced 
cardiac life support (PALS), or neonatal advanced 
cardiac life support (NALS). as appropriate to the 
circumstance. They should also be educated in aer- 
omedical physiology and understand the eftect that 
altitude has on team members and patients. 

Extensive knowledge about specific aircraft — 
including safety features, regulations, and capa- 
bilities — is important for safe transports, as well as 
in times of flight emergency. One of the most 
important kinds of information is hov\ to load and 
unload a patient quickh and safely (Fig. 2). This 

Fig. 2. The transport team making preparations to load a 
patient into a roto-wIng aircraft. 




can be the source of problems if adequate training 
and forethought are lacking. Delays and disaster 
have occurred as a result of such lacks. Man- 
agement of the patient's airway is a frequently used 
skill that demands expertise: thus, at least one 
member of every team should be highly capable in 
this regard. In the LDS Hospital program, cross- 
training of nurses and paramedics has enhanced the 
abilities of both kinds of personnel in emergency 
care, rescue, and critical care. 

Responsibilities and Skills of RCPs 

The duties of RCPs involved with air medical 
transport vary with the programs with which they 
are affiliated. However, some universal responsibil- 
ities can be listed: ( 1 ) assembling, checking, and 
stocking respiratory transport equipment: (2) mon- 
itoring, maintaining, and filling liquid-oxygen sys- 
tems for transport, unless otherwise directed by 
flight regulations: (3) assessing the patient's oxy- 
genation and ventilatory needs: (4) airway man- 
agement: (5) oxygen administration and/or ven- 
tilatory support, including monitoring and 
managing the ventilator: (6) ongoing patient mon- 
itoring and assessment: and (7) helping other team 
members when necessary and feasible. 

Airway Management 

As previously stated, airway management (spe- 
cifically intubation) has been a topic of con- 
troversy. Who should intubate? How much training 
should be required? Under what circumstances 
should intubation be performed? The life-saving 
effectiveness of intubation and a properly main- 
tained endotracheal tube (ETT) have been doc- 
umented for years.'""''' The major controversy is 
whether team members other than physicians 
should perform emergency intubation. According 
to Leicht et al,''' flight crews (nurses, RCPs, and 
paramedics) must be proficient at intubation. Train- 
ing for intubation at LDS Hospital mandates 20 
successful intubations in the operating room ini- 
tially before flying, 10 per quarter thereafter, and a 
total of 40 successful intubations per year. All roto- 
wing team members (excluding the pilot) are 
required to maintain this skill quarterly. 

Stabilization of the ETT following intubation is 
equally important. Various methods that have been 

proposed to effectively secure the airway include 
the use of adhesive tape, clamps, plastic tubing, 
commercially available ETT holders, and cloth 
tape. Zecca et al" concluded in their study that the 
use of a commercial ETT stabilization device was 
the most desirable alternative because of a shorter 
application time and better security and stabiliza- 

Technology and Equipment 

Equipment Adequacy 

"Critical Care Monitor Nearly Kills Medical 
Patient." So stated the title of an editorial in the 
February 1991 issue of the Journal of Air Medical 
Transport }*" The author described the near-fatal 
results when an air medical team responded to 
alarms on a cardiac transport patient by admin- 
istering a drug, only to discover thereafter that the 
alarm warnings had been erroneous. As monitors 
and other life-support equipment have become 
more compact and transportable, their use outside 
the hospital has increased. Many assume that 
equipment that has been modified and miniaturized 
for ground transports is ready and capable for 
flight-transpoil use. However, this assumption is 
not always correct, and the use of such equipment 
may be detrimental or fatal. 

When air medical transport was in its infancy, 
many hours were spent in testing and adapting 
equipment to be used in aircraft. As altitude and 
work space changed, so came the need for equip- 
ment modification by flight-team members. Med- 
ical-equipment manufacturers historically have not 
concentrated on the specialized needs of air trans- 
port. However, recently, the response to these spe- 
cialized needs has greatly improved. The field of 
biomedical technology has grown and now 
includes the aeromedical specialty. There are now 
pulse oximeters that synchronize with the R wave 
in an ECG to decrease the effects of motion and 
background artifact." Intravenous pumps and mon- 
itors are now taken on flights. CO; monitors, blood 
pressure monitors, cardiac monitors, and many 
combinations of several monitors are all packaged 
for flying"*" — which can sometimes lead to a 
great deal of confusion when one is trying to 
decide what to purchase. 




Testing and Evaluation 

Before any pieee of ei|uipnieiit is used for 
patient care, it should be flight-tested and evalu- 
ated. Pertinent Federal Aviation Administration 
regulations must be met. and the nidi\idual air 
transport program's needs must be determined. 
Most equipment \endors aid this evaluation pro- 
cess by lending devices, support hardware, and 
technical support. 

How Much and How Many? 

Another concern is. How much should you take 
on a flight and how many of a given device do you 
need? The answers to these questions can best be 
found through a tlight team's own experience and 
that of other well-established teams. Life Flight 
protocols at LDS Hospital have undergone several 
transformations o\er the years. Important questions 
intluencing the decisions made about each device 
were ( 1 ) Will it pass air-safety standards? (2) Is it 
necessary on most of our common transports? (be 
adaptable). (3) What is the experience of other 
tlight programs? and (4) Is it versatile, dependable, 
user-friendly, and necessary? 

Transport Ventilators 

The search for and evaluation of transport \ en- 
tiiators is of great interest. We have looked for the 
ideal transport \entilator for nearly 10 years, but 
with very limited success. Experience has shown 
tiiat what is acceptable for one type of patient or 
ventilatory mode is inadequate in other ways. Sev- 
eral "portable" ventilators are on the market for 
transport, with a few e\a!uations reported.-' -"■ An 
in-depth evaluation of several transport ventilators 
by Branson and McGough-^ statctl that 

Transportation of ventilator-dependent patients is facil- 
itated by the use of transport ventilators. Considerable 
variations exist regarding the ventilator)' characteristics 
and advantages and disadvantages of these devices. No 
one transport ventilator is suitable to all situations. Prior 
to choosing a transport ventilator, the following factors 
should be addressed; the airway pressure, flowrate. and 
volume characteristics under conditions of changing 
lung mechanics; demand-flow capability for spontane- 
ous breathing; monitoring of airway pressure; modes of 

ventilation; Fio:; ease of operation: cost: size: gas con- 
sumption; and the types of patients for whom the ven- 
tilator is intended. 

In the Respiratory Care Department at LDS Hos- 
pital, we have evaluated most of the ventilators on 
the market. Currently, we use a modified Bird 
Mark 14 ventilator. A description of the mod- 
ification was published in 1979.-'" This ventilator 
has brought many a smile to those at a referring 
hospital when our flight team has arrived to pick up 
their patient. On one occasion we were met with 
unrestrained laughter — until the first blood gas val- 
ues were obtained after the patient had been trans- 
ferred to our "old Bird." Then the laughter sud- 
denly subsided, and the room quickly cleared of 
curious onlookers. The Bird is somewhat tempera- 
mental, but its performance is superior to anything 
we have tested. It requires close surveillance and 
consumes approximately 6.5 L/min of oxygen 
when operating at higher minute \ entilations. How- 
ever, it will ventilate an ARDS patient with a tho- 
racic lung compliance of 6 mL/cm H;() and per- 
form exceptionally well at an altitude of 25,000 
feet for hundreds of miles. Unfortunately, the mod- 
ifications (which were performed with permission 
from Dr Forrest Bird) are no longer performed, and 
one repair part is no longer manufactured. 

Pediatric/Neonatal Transports 

The transporting of children brings another set 
of challenges. Salyer has expressed his concern as 
to whether adult transport teams recei\e enough 
training in the pediatric specialty and whether these 
team members perform an adequate number of 
such transports to maintain pediatric skills.-^ He 
suggests that transport ser\ices woukJ best meet the 
needs of the pediatric/neonatal population b_\ aug- 
menting their programs with nurses, RCPs, and 
emergency medical personnel who have been spe- 
cifically trained in these specialties. 

For the Life Flight program, a pediatric tlight 
team is stationed at Primary Children's Medical 
Center (also a member of IHC Coiporation. along 
with LDS Hospital) for all pediatric transports. At 
LDS Hospital, we have chosen to stock a separate 
pack with pediatric supplies. These packs are kept 
ui both oiu- helicopters, as well as at the ground sta- 
tion at Prmiary Children's Medical Center. 




Adverse FlfTects of Air Triuel 

Along with all the [xisiiisc (Uitcomes of air med- 
ical transport, which are due to quick response, 
reduced prehospital time, or intensified care at spe- 
cialized centers, one is also keenly aware of the 
possible adverse effects of air travel. In addition to 
the possibility of equipment malfunction or failure. 
there are also possible physiologic implications that 
may be intensified by altitude change, gravity 
forces, decreased humidity, and sudden movement. 
It has been show n that there is a greater risk of air- 
way occlusion because of secretions and decreased 
humidity.-'* Occasionally I have seen an increase in 
subcutaneous air or enlargement of a pneumo- 
thorax, due in part to cabin pressure that is lower 
than ground-level pressure. However, I believe that 
a well-equipped, well-trained transport team will 
foresee most potential problems and appropriately 
treat those that are intensified by air travel. Of 
course, probable patient outcome without transport 
must be weighed against possible risks associated 
with air transport when decisions are made con- 
cerning patient care and air transport. 


No air medical accidents were reported in 
199() — a statistic for which all flight-team members 
are grateful. But this welcome piece of good news 
was quickly overshadowed in 1991 by a tragic acci- 
dent in Sayre. Pennsylvania, in which four dedi- 
cated fliers were killed. Safety must be the most 
important factor in any air medical program. Each 
team member shares the responsibility for a safe 
flight and an accident-free program. Along with 
continuous quality improvement of patient care. 
team-member skills, aircraft maintenance, and 
flight operations — safety audits are paramount to 
the safe operation of an air medical transport ser- 
vice. Whether this is done by in-house audits or by 
seeking the assistance of independent sources, 
improved safety must be the Nuinber One objec- 
tive.-^-^" Although air medical accident rates have 
dropped significantly since hospital-sponsored pro- 
grams began in 1972," there is still a need for con- 
stant safety monitoring. 

According to Lillie and Larson.'- some factors 
influencing the decrease in accident rates are (1) 

managerial commitment and an increased emphasis 
on safety. (2) safel\-ci)mmittee reviews. {?>) better 
equipment, (4) more experienced personnel, (5) an 
established relationship with first providers of 
emergency care that helps with landing-site prepa- 
ration, (6) better adherence to policies and pro- 
cedures. (7) improved training, and (8) less demand 
to fly under marginal conditions. The last point is 
probably one of the key factors influencing the 
safety record of LDS Hospital's Life Flight .service. 
Our policy is to never put pressure on a pilot by 
informing him of the condition of the patient or the 
severity of an accident. The pilot is to make a deci- 
sion to fly or not to fly based on his knowledge of 
environmental factors and the abilities/limitations 
of the aircraft. If a pilot states that conditions are 
not favorable and safety is jeopardized — we don't 

Another important aspect of safety is pre- 
planning and computation of safe and legal takeoff 
weight and center of gravity. Accurately calcu- 
lating the weight of the equipment, team members, 
and patients — and the effect that placement has in 
relation to the center of gravity — is of paramount 
importance for safe takeoff and landing. '^ It is the 
team's responsibility to the pilot of the 
weights and positions of the patient, equipment, 
and team members — then not to deviate from these 
positions, such as by moving a gas cylinder, with- 
out prior notice to the pilot. 

Utilization and Professional Associations 

Utilization of Plight Services 

According to a survey made by the Joiinuil of 
Air Medical Tninsport (JAMT), more than 1 mil- 
lion patients were transported by air medical teams 
from 1972 through 1990. with 159,027 of these 
patient being transported in 1990.''"' The 1990 data 
for the LDS Hospital Life Flight program show that 
we transported 1.360 patients, of whom 609f were 
adult and 40% pediatric/neonatal, as shown in 
Table 2. 

The number of hospital-based programs offering 
helicopter transport grew from 101 in July 1985 to 
178 in July 1991.''-'' According to the 1991 survey 
of flight programs conducted by JAMT. the number 
of transport team members employed by hospital- 




Table 2. Percentages of Patients, by Category. Transported in 
Roto- Wing and Fi.\ed-Wing Aircraft during 1990 by 
LDS Hospital Life Flight in 1.236 Air Transports* 























No. of patients 



* Of the 1.236 patients, 409!; were pediatric and 60% adult. In addition 
to the 1.236 patients transported by air, 124 patients were transported 
by the flight teams via ground \ehicles. 

t Including overdose and carbon monoxide poisoning cases. 

sponsored programs increased from 5,341 in 1988 
to an estimated 6.828 in 1991.-'' RCPs were not 
specifically identified in this survey, but JAMT is 
considering revising the 1990 survey to specifically 
identify RCPs as team members (personal com- 
munication, August 1991, from Brian Larsen, Edi- 
tor of V/IMD. 

Professional Associations 

Currently there are several national associations 
for the various flight-team members, including the 
Association of Air Medical Services {AAMS). the 
National Flight Nurses Association (NFNA), the 
National Flight Paramedics Association (NFPA), 
and the National EMS Pilots Association (NEM- 

Benefits/Risks for Personnel 

After all is said and done — why do people tl>. 
why do they risk their lives, suffer airsickness, 
headaches, and fatigue, and place themselves close 
to hazardous situations'.' Is it all worth it? Yes, it is. 
The turnover rate for flight nurses rose from 1.1% 
in 1988 to 1.8% in 1990. which indicates that 
things are not ideal all of the time, but in compari- 

son to turnover in other professions, the rate is 

The challenges are endless, yet the reward of 
seeing a fellow human being receive life-saving 
care because of your efforts is a big factor that 
weighs against the risks. The stress is intense, and 
the hours are sometimes unfavorable, but, overall, 
people train and practice and take risks and \^\ 
because they like it. 

In Conclusion 

Experience has shown that safe and successful 
transport of the critically ill or injured by helicopter 
and fixed-wing aircraft is successful when per- 
formed by a team of highly skilled professionals 
who have received additional training in tlight 
travel, safety, aeromedical physiology, loading 
techniques, and field survival. The airborne trans- 
port teams that have been organized during the past 
20 years have made a positive difference in patient 


1 thank the directors and staff members of the LDS Hospital 
Life Flight program for their contributions to this paper, and 1 
thank Connie Easterbook for assisting in the compilation of 
this work. 


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Jeffs Discussion 

Masferrer: It's real interesting to 
me to see you show those slides with 
the Mark 14s and the Bird humidifi- 
ers. When people talk about transport 
ventilators they never mention those 
machines. I'm Just curious. Why is it 
you guys don't look at those 

machines? [Referring to Branson] 
You're always looking at everything 
else and giving opinions on every- 
thing else; I'd like to hear your opin- 
ions about that type of ventilator 
v\ hen you move patients around. 
Branson: I personally don't always 
advocate that kind of thing. I know 
that the people in Salt Lake are very 

proud of the fact that they've mod- 
ified the Mark 14 to work for them, 
and that's really great. We do the 
same thing, only with a Mark 2 and 
two inspiratory flow cartridges — 
available long before the Bird Mark 
7 was even invented. With those, I 
can ventilate any patient in the entire 
world. The problem is, / can do it, 




and / have the eciuipment. and / can 
make sure that it works, and / can do 
all those things, but it's not the same 
for everybody. I think you actually 
sometimes do a disservice to the 
community by saying. "This is 
what's commercially available, and 
you can buy it. But, come down and 
see me, and I'll modify this so it'll 
do anything you want it to do." And 
then there's the problem of once 
you've modified it, what's the liabil- 
ity? Now. 1 personally don't concern 
myself with that, but I know when 
we have modified things, we have 
gotten calls asking what happens if 
the patient dies during use? Who's 
going to pay? The manufacturer is 
not. I don't know that that's a Bird 
Mark 14. to be honest with you. It 
looks like a Bird ventilator with 
demand CPAP. I'm sure Dr Bird has 
two dozen or more of those sitting in 
his office somewhere, and you can 
probably get one from him. And 
those things will ventilate anybody! 
You know, pressure control was 
introduced by Dr Bird in 19.'i8. and 
now we're doing it on everybody 
like it's brand new. Those machines 
will work. The problem is the avail- 
ability. Are there enough people 
skilled to use it? When you guys 
(Ray) were doing therapy in the 60s. 
if a Mark 7 were to fall apart, 909( o\' 
the people in the department could 
fix it on-site. That's not true today. 
Masferrer: That's a good point. 
.Jeffs: If I could address that as well, 
and Rich (Branson) makes a very 
good point. It's not available. The 
modifications were made with the 
help of Dr Bird. He's very aware of 
those modifications and in fact 
helped make them. The point that 
you made — that you can run some- 
thing when no one else can comes 
down to that Bird as well. Basically, 
our therapists can run our ventilator, 
but not all of our therapists run it 
well. There are a few select ther- 
apists who run it very well: but. is ii 
easily put together if you drop it? 

Heavens, no. Is it easily used? No. 
It's the most temperamental little 
beast, and you have to monitor it 
constantly. So. that's why we search 
for a machine that has those capa- 
bilities but isn't so difficult to use. 
isn't so difficult to find, and is more 
available to trauma centers that need 
a ventilator that can ventilate dif- 
ficult respiratory patients. But. nou 
make a very good point. Richard. 
Reines: 1 trained with Joe Cixetta 
and Bob Kirby in Miann when we 
used Super PEEP, and the truth of 
the matter is. in an I.IOO-bed hos- 
pital in which we have the highest 
number of patients involved in the 
new surfactant study, we haven't 
gone over 25 of PEEP, and we're 
running a 38% mortality rate. 1 
wouldn't have any use for thai \en- 
tilator. except maybe twice a year. 1 
don't often need to use that much 
PEEP, and I don't need to use that 
fiowrate any more. I used to do that 
20 years ago when I used the Mark 
14 or Mark 7. with a series of fiow 
caitridges that only Mike Banner and 
Bryan DeHaven and a couple of 
other people know how to do; so I 
don't see a use for it \ery much any- 
more. I really don't think you're 
going to get a manufacturer to make 
it because I don't think most of us 
need it. 

Hurst: That might be true; however, 
remember that during aeromcdical 
transport, the transport team does not 
have the same control of the patients' 
environment that we do in the hospi- 
tal. We know how our own patients 
h;i\c been resuscitated. We know 
how they've been treated, ^'ou and I 
have both gotten patients from out- 
lying facilities that have not been 
managed well. The need to salvage 
those patients, to rescue those 
patients, to place them on an extraor- 
dinary support de\ice may he indi- 
cated. There will always be that 
small group of patients who fall out- 
side the en\ elope. I'm an advocate ot 
our being able to use these special- 

ized devices. 1 think these special- 
ized de\ices belong in tertiary refer- 
ral centers — where we can commit 
the resources of a specialized team 
because of the labor-intensive nature 
of these devices. Now. I'll get off my 

Weaver: 1 think I can express the 
same sentiments. We're a referral 
hospital for an ARDS clinical trial. 
We've recei\ed patients from as far 
away as Florida. In fact, 2 came from 
Florida. We had 8 or 9 from Cal- 
ifornia, but we're looking at patients 
who met ECMO-entry criteria, with 
mean lung compliances between 7 
and \^. Our lowest pulmonary com- 
pliance was 2. That patient ended up 
on 55 cm of PEEP, and that patient 
died. We had another patient who 
had Po:S of 23 and 24 toiT. in cir- 
culatory shock, on 25 cm H:0 of 
PEEP, and we increased PEEP to 35 
cm H;0. Our protocol was to never 
go above 25 of PEEP. We went to 
35. and her Pq: went into the 50s. 
We were able to back dow n on pres- 
sors. Now, that's I person out of 40. 
But, again. 1 think if you're a referral 
hospital, and you're looking at 
ARDS patients w ith stiff lungs, occa- 
sionally you're going to need a ven- 
tilator that exceeds the capabilities of 
what's presently available on the 
market. If you don't ha\e that ven- 
tilator, how do Nou deal with the 
problem? How do you transport the 
patient to CT? You can't. Even in 
our extracorporeal group, we actu- 
ally developed a portable cxlraciir- 
poreal circuit, so that we could mo\e 
the patient to CT. We recognized 
that we might need to drain an 
abscess, percutaneously. or some- 
thing. We never did. thank goodness; 
but we had the capabilii\ of doing it. 
So. 1 think, again, in a reterral hos- 
pital, where you expect to see a num- 
ber of such patients, technology is 
not to the point where 30U can ven- 
tilate some of these patients, and 
that's why we use an 'anlit|iialed' 
mechanical ventilator for transport. 




This ventilator that we use in air 
transport is the same one we use in 
the hospital. I think that works out 
quite well because it keeps the ther- 
apists who are flying current in the 
use of this machine, which is quite 

Reines: I just want to warn you that 
the hability question is a very real 
one. that one of the reasons we 
stopped jury-rigging is because of the 
FDA. If anything goes wrong on that 
machine, and the patient has a mis- 
hap, you don"t stand a chance. 
Weaver: I don't doubt that. That 
ventilator has been used in our hos- 
pital since 1974. and I'm not the one 
who modified it. 

Masferrer: But what is the differ- 
ence with a modification of a ven- 
tilator like that going wrong and one 
of the ones that Rich (Branson) 
showed us during his presentation 
going wrong and failing? You still 
have the same liability problem, 
don't you? 

Reines: I'm just saying that when 
)ou mt)dif\ a \entilator that much, 
the manufacturer has no responsibil- 
ity. All of it falls on the hospital. 
Jeffs: Your point is well taken, and 
that's why we're looking for some- 
thing else. I'm not advocating this be 
sold on every corner, at all. I'm not 
advocating that just anybody run it, 
either. I'm just simply saying that 
there is a place for it. and there is use 
for it. and 1 wouldn't have anything 
else at 25,000 feet when I've got a 
patient with a compliance of 4. I've 
moved those patients thousands of 
miles when the referring facility 
couldn't move them to their t)wn CT 
scanner. I've seen them live. They 
come back in and bring us choc- 
olates. It is a reward to me to see 
patients live when their prognosis has 
been very poor. But your point is 
well taken, and I do appreciate that. 
Hurst: 1 understand the question of 
medical liability; 1 really do, Dave 
(Reines). Maybe I'm stupid, and 
maybe I'm lucky, or maybe it's true/ 

false and unrelated. I just absolutely 
refuse to practice medicine looking 
over my shoulder and waiting for the 
other shoe to drop. I'm well aware of 
the fact that in the trauma and critical 
care environment, it will probably 
catch up with me. Maybe 5 or 10 
years from now, I will have a differ- 
ent mind-set, but right now I guess 
I'm too much of a rebel to accept that 
as an excuse not to be on the cutting 

Branson: We can get into a contest 
over ventilators and ventilating 
patients. Jim (Hurst) and I have been 
in the air, on the ground . . . 
Hurst: Uiulerlhe bed! 
Branson: Yeah, under the bed, on 
many occasions, with all kinds of dif- 
ferent ventilators. You just have to 
understand that I don't mean to say, 
"Oh, your ventilator doesn't work, 
and it's a bad idea for you to do 
that." .■\ll I mean to say is, "It's great 
that you use it, but it's not like some- 
body's going to be able to replicate 
the way you do it," unless Dr Weaver 
transfers to the University of Cin- 
cinnati and brings one with him. I 
mean that's the way those things hap- 
pen. But, for the most part, we're 
going to have to live within the con- 
straints that we have. 
Jeffs: I disagree. 

Branson: And help people buy 
things that they can use that meet 
their needs. I mean. I've used the 
Uni-Vent 750 to ventilate patients 
w ith up to 35 cm of PEEP, with bilat- 
eral bronchopleural fistulas, on IMV, 
without any trouble. I think I'm get- 
ting pretty good at this, and I've also 
done it with that little Bird \entilator 
in the air for 2 hours. We all have our 
anecdotes, but when it comes down 
to the other 50 or 60 air medical pro- 
grams or transport programs or what- 
ever, they're not going to do that, and 
they have to have another choice. 
The answer may be that the man- 
ufacturers have to come up with 
another ventilator or therapists just 
have to learn to use what's available 

within the constraints of that ven- 

Jeffs: Yes, but what I'm saying is 
that I don't feel like we need to be 
limited by current constraints. I'm 
saying that our constraints could be 
addressed. I feel like they can. I'm 
heckling Puritan-Bennett to death to 
work with me on developing a trans- 
port ventilator that has the desired 
capabilities. The last time I flew into 
Bakersfield, for example, the pulmo- 
nologist said. "You can take my 
patient, but you need to leave your 
ventilator here." This was the third 
patient we had picked up from his 
facility, not because they couldn't 
handle the patient and do a lot of 
good things there. They could — but 
in this particular instance, he wanted 
to take her to CT and wasn't able to 
get her there. He tried 5 times, then 
he asked us to come in and pick her 
up. When he asked that the ven- 
tilator stay, I said. "I'm sorry, but the 
ventilator goes where I go." He said, 
"No, you can take my patients, but 
you've got to leave that ventilator 
here." So, there aie people who want 
the capabilities. They don't want this 
archaic device, necessarily, but they 
want the capabilities. 
Hurst: There'll always be those spe- 
cialized needs. I'm sorry, Sam, go 

Giordano: I wanted to talk about 
something related to tran.sports. so . . . 
Hurst: There'll always be those spe- 
cialized needs. If each one of us puts 
himself in the position of the equip- 
ment manufacturers, it's not worth it 
to them from a cost-benefit stand- 
point to engage in that kind of 
research and development, so that 
you have your ventilator, and I have 
my ventilator, while everybody else 
in the country is using something 
else. I think the moral of that story is 
that there'll always be somebody out 
there who will create toys for you 
and me to play with. 
Jeffs: 1 posed that question to Puri- 
tan-Bennett because they said the 




same thing to me. I asked them to 
please survey the market or at least 
survey some tertiary care centers. 
The representative called me back a 
week later and said. "OK. let's talk 
about your ventilator." There are 
people who want it and who need it. 
Giordano: Now. if I could interject a 
different note. I'd like to think that 
the AARC is the organization for res- 
piratorv care practitioners. Several 
years ago. we formed a specialty sec- 
tion for persons involved in air trans- 
port. I'd also like to add thai within 
the last 2 years, the Commission on 
the Accreditation of Aeromedical 
Services (CAAMS) has been formed 
for the purpose of developing stan- 

dards for accreditation of medical 
services, which I believe that picture 
you showed of the crashed helicopter 
shows there's a need. I submit that 
the Association, the AARC, does 
have representation on the CAAMS 
board of directors. So, I think that the 
profession is beginning to establish 
presence within the realm of air med- 
ical services; however, I think some 
of us realize that with the ever- 
increasing interest in multiskiiied 
practitioners, that for the respiratory 
care practitioner to be qualified at the 
optimum le\el, that indi\ idual should 
be fully cognizant of the environment 
that he or she works in (vis-a-vis the 
helicopters or the airplanes) but, also. 

should probabK acquire EMT skills. 
Let's think in terms of the cost- 
effectiveness. 1 think it's indis- 
putable that you should have a reg- 
istered nurse on transports; however. 
1 do feel that a qualified respiratory 
care practitioner with EMT training 
as well as qualifications in res- 
piratory care is a better value to the 
institution that employs that indi- 
\ idual than is a therapist with a sin- 
gle credential. I encourage our col- 
leagues to acquire the additional 
training, rather than to try to muscle 
their way on as third persons 
because it's always the odd person 
out in that particular instance. 
Jeffs: I wouldn't disagree at all. 
Good comment ! 



Emergency Respiratory Care: Conference Summaiy 

Charles G Dm bin JiMn 

Setting; the Stage 

The theme of the 1991 Respiratory Care Jour- 
nal Conference '"Emergency Respiratory Care'" 
brings hack memories of why 1 entered the practice 
of medicine in the first place. I remember an inci- 
dent that occurred when I was in high school — I 
was the first to arrive at the scene of an automobile 
accident, and 1 didn't know what to do. I comforted 
the trapped victim and waited for help to arrive. 
When the volunteer paramedics arrived, they 
quickly and efficiently asses.sed the victim's condi- 
tion, determined that it was stable, and set about 
removing her from the vehicle. Their calm, com- 
petent demeanor remains in my mind. I strive for 
that same appearance of competence and calm in 
my daily practice. 

In order to perform effectively in an emergency 
situation, knowledge and skill are needed: how- 
ever, the knowledge needed is not vast — perhaps 
unlike many branches of medicine. Most lifesaving 
skills are simple, but they must be learned and 
practiced before they are needed. The purpose of 
this conference was to identify the skills and 
knowledge unique to the practice of respiratory 
care that are essential in emergency situations. The 
clinical areas in which crucial events frequently 
occur were chosen as topics. The conference was 
organized much like a resuscitation plan: A — 
Airway, B — Breathing (ventilation). C — Cardiac, 
and T — Transport. Points of consensus and topics 
needing more study were identified. 

Dr Durbin is Professor of Surger>' and Anesthesia, and Med- 
ical Director of Respiratory Therapy. University of Virginia 
Medical Center. Charlottesville. Virginia. 

A version of this summary was presented by Dr Durbin at the 
conclusion of the Respiratory Care Journal Conference on 
Emergency Respiratory Care held in Cancun, Mexico. October 
3-5, 1991. 

Reprints: Charles G Durbin Jr MD. Dept of Respiratory Care, 
Box 402, Univ of Virginia Health Sciences Center. Charlottes- 
ville VA 22908. 

Emergency care crosses many formal dis- 
ciplines, and a wide range of experts were selected 
to participate in this conference — respiratory care 
practitioners (RCPs), managers, and researchers. 
The discussions were lively and. at times, heated. 

One goal was to identify topics for research by 
the respiratory care community that could improve 
the knowledge and the practice of emergency 
care. In addition to briefly summarizing each pres- 
entation, 1 identify at least one facet from each 
presentation that I believe needs further study — 
facets appropriate for RCPs to pursue. 

The proceedings of this conference fill a gap in 
the respiratory care literature. The papers outline 
the respiratory and nonrespiratory emergencies in 
which an RCP can contribute to improving patient 
care. A fonnidable and current collection of refer- 
ences accompanies each paper. The participants 
selected were asked to stimulate critical examina- 
tion of what is known, what is unknown, and what 
needs further study. The discussions following 
each paper are the result of this effort. 

Emergency care, respiratory or otherwise, is a 
team sport. Teams require a game plan, and prac- 
tice improves performance. In real life, the team 
may consist of people who have never met one 
another but who through common training and 
standardized protocols are able to utilize their 
resuscitation skills quickly and appropriately when 
necessary. More important than educational back- 
ground or credentialing is familiarity with com- 
mon, simple standard practices. From this phi- 
losophy, nationally recognized certifications in 
basic life support (BLS), advanced life support 
(ACLS), advanced trauma life support (ATLS), and 
pediatric advanced life support (PALS) are prom- 
ulgated. With these response plans, team members 
must be able to fill any of several roles. RCPs, 
nurses, and physicians can be certified through 
many of these programs indicating that they have 
achieved a minimal acceptable skill and knowledge 
level. Certification of RCPs in BLS and ACLS is a 




step toward gaining recognition of our abilities and 
commitment to emergency care equal to that of 
other practitioners. Most of the presenters at this 
conference are certified in BLS and ACLS, many 
as instructors. 

The Role of the RCP 

The first paper was presented by Robert Kac- 
marel;. Bob defined the role of the RCP in emer- 
gency situations. He presented data on field intuba- 
tions by emergency inedical technicians (EMTs), 
showing them to be reasonably competent. 
Although no data on RCP performance of endo- 
tracheal intubation exist, every critical care ther- 
apist should be capable of and competent at intuba- 
tion. That's a controversial statement, but it is one 
on which the group easily reached consensus. 
Although each institution has different job respon- 
sibilities for its RCPs and many institutions do not 
routinely include intubation among those respon- 
sibilities, in an emergency the RCP may need that 

RCPs are particularly competent in respiratory 
system assessment. Assessment of airway pressures 
and respiratory mechanics are obvious applications 
of skills and tools used daily. Determinations of 
flowrates in asthma and exhaled volumes during 
CPR are two obvious examples. Drug delivery 
through the endotracheal tube (advocated by the 
American Heart Association in the absence of 
intravenous access) is an obvious topic for research 
by the respiratory care community. We need to 
know whether metered dose inhalers can be used to 
deliver epinephrine for resuscitation. The use of 
mechanical \entilators in and the most effective 
modes of ventilation for resuscitation need to be 

Upper Airway Problems 

Roger Wilson began his presentation on intuba- 
tion with a depressing statistic — the high frequency 
of failed elective endotracheal intubations at the 
hands of experienced anesthesiologists (in con- 
trolled operating room circumstances). Quoting a 
rate of failed intubations as low as 1 in 2,000 and 
as high as 1 in 300 (in pregnant patients), he 
emphasized that attention to simple points such as 

oplinuim head position are most likely to improve 
success rate. He also discussed scoring systems for 
predicting difficult intubation. Despite elaborate 
methods, no systein is able to predict w ith certainty 
those patients who will be difficult to intubate. The 
effects of abnormal anatom\. pathology (eg. 
tumors), and airway edema were discussed. Alter- 
natives to oral endotracheal intubation such as ret- 
rograde catheter introduction were suggested. The 
use of muscle relaxants (and their pharmacology) 
and acute and long-term complications of intuba- 
tion were presented. 

Potentially fruitful topics for research are assess- 
ment of the competence of individuals to perform 
intubation and detemiination of how man\ intu- 
bations in what time period are necessar\ to main- 
lain operator competence. The success of RCPs as 
a group in performing endotracheal intubations 
needs to be established. 

Acute, Severe Asthma 

Chris Fanta presented a patient with asthma and 
described what was believed to be appropriate 
treatment 10 years ago. From this Chris then out- 
lined what has changed. He made clear where we 
are and w here we should be regarding drug therapy 
and monitoring in the treatment of asthma. .Amino- 
phylline has little or no place in acute treatment. 
Inhaled bronchodilators. primarily beta agonists, 
are the mainstay of treatment today. Doses need to 
be based on patient response and are generally 
higher than has been felt to be safe in the past. 
However, we reallv don't know what doses are 
appropriate — both with the old and the newer 
delivery systems. The role of aniicholineigics in 
acute management is not always clear. Steroids are 
essential in patients who fail to respond to beta- 
agonist therapv in a reasonable period of time — an 
hoiu or so of appropriate treatment. Steroids appear 
to exert their therapeutic effect by decreasing air- 
way edema, restoring beta-receptor responsiveness, 
and by some other poorly understood mechanisms. 
Whether all patients should receive steroids for the 
emergency treatment of asthma is not clear. Anti- 
biotics are not indicated in most asthmatic patients; 
they should be reserved for patients who have a 
documented infectious process, not just discolored 




An important role for the RCP in the man- 
agement of acute asthma is monitoring of pul- 
monary function. Arterial blood gas values (ABGs) 
should be used more frequently to evaluate the 
severity of gas exchange impairment in asthma. 
The forced vital capacity. FEV,. and peak tlows are 
much more sensitive lo changes in airway disease 
than are clinical assessments or subjective impres- 
sions of the patient. RCPs can train patients to 
make peak expiratory' tlow measurements at 
home — to monitor disease progression and identify 
the need for more intensi\e therapy. 

Massive Hemoptysis 

James Stoller presented "MassiNe Hemoptysis" 
indicating that the various definitions of the term 
complicate rational discussion and formulation of 
appropriate treatment plans. Everj'thing from 
repeated small amounts of bloody sputum to exsan- 
guinating hemorrhage has been called massive in 
the literature. The two major problems with mas- 
sive hemoptysis are airway obstruction (with con- 
sequent asphyxia) and hemodynamic compromise 
from blood loss. The bleeding site (pulmonary or 
systemic circulation) gi\ing rise to hemoptysis has 
a dramatic influence on the se\erity and on the 
choice of treatment. Surgery, medical management, 
and recently de\eloped radiographically controlled 
embolization of bleeding sites were contrasted. 
Jamie presented a systematic approach to manage- 
ment and described other treatments including top- 
ical lavage with vasoactive fluids introduced 
through the bronchoscope and intra\enous infusion 
of vasopressin. 

The appropriate use of mechanical ventilation 
and PEEP in patients with hemoptysis needs eval- 
uation. The use of PEEP in pulmonary artery (P.A) 
rupture (as with P.A-catheter balloon-induced rup- 
ture) has been suggested but never subjected to 
study. Animal experiments are needed, although 
caution regarding application of results is necessary 
because of the interspecies differences in pul- 
monary vascularity. 

Pediatric and Neonatal Emergencies 

John Thompson described some pediatric and 
neonatal emergencies, identifvinc the differences 

between infants and adults in closing volume, oxy- 
gen consumption, and tracheal size. These differ- 
ences lead one to rcali/c thai when airway com- 
promise occurs in infants, the margin of safety is 
much narrower than in adults. On the other hand, 
infants and children usually don't have coronary 
artery disease, thus, the likelihood of survival once 
an airway has been re-established is much higher. 
A resuscitation algorithm based on the Apgar score 
for neonates was discussed. Apgar scores have 
been around for 40 years or more and are still use- 

Self-intlating resuscitator bags can present prob- 
lems during newborn resuscitation because the 
pressure-relief valves may not allow the develop- 
ment of pressure adequate for the initial inflation of 
the lungs. Once initial inflation has occurred, man- 
ometric monitoring is essential during manual ven- 
tilation to avoid excessive airway pressure and yet 
guarantee adequate \ entilation. 

John then described diaphragmatic hernia and 
the methods used for management of this condi- 
tion, which catastrophic derangements in 
gas exchange. He next discussed croup and epi- 
glottitis in the pediatric population, differentiation 
between the two. and appropriate airway man- 
agement. An important contribution that RCPs can 
make to the pediatric and neonatal environment is 
to develop and evaluate appropriate methods to 
secure the endotracheal tube. Inad\ertent extuba- 
tion is a frequent occurrence and an important haz- 

Drowning and Near-Drowning 

Martin Nemiroff presented information on 
drowning based on his personal experience with 
more than I .()()() episodes. \'oung age and the pres- 
ence of sedative drugs (including ethanol) are indi- 
cators of a good prognosis in patients who have 
sustained long immersion (> 7 min) in cold water 
(< 20°C). In very cold water, the absence of strug- 
gling appears to preserve protective energy. Unpol- 
luted water also makes for a better outcome. 
Attempted suicide by drowning carries a poor prog- 
nosis and is often complicated by other injuries. 

Because there have been many recorded normal 
survivors after 45 minutes or more of submersion 
in cold water. Marty stated that the standard of care 




is aggressive resuscitation for any person immersed 
for 60 minutes or less. The presence of fixed and 
dilated pupils is to be expected and is not indicative 
of a bad outcome. Active rewarmint; during trans- 
port is discouraged because rewarming arrhythmias 
can complicate the resuscitation. Rewarming with 
endotracheal aerosols is effective and temperatures 
as high as 107°F are used. Skin burns remain an 
important problem when surface re wanning is 

Research is needed on the treatment of the coag- 
ulopathy associated with hypothermia. Uncon- 
trolled bleeding that requires large amounts of 
blood and blood products is a common occurrence. 
A subject for research more rele\ant to the res- 
piratory care community is the optimal man- 
agement of ventilation and oxygenation during 
transport and rewarming. Initial ABGs are mark- 
edly abnormal but ha\e not been evaluated in any 
systematic fashion. 

Smoke Inhalatiuii 

Ed Haponik discussed smoke inhalation injury, 
commenting that upper airway edema causing 
abrupt airway obstruction (making intubation 
essential but almost impossible) is a frightening 
occurrence. Despite the classic teaching, signs of 
airway injury are often absent. The presence of 
facial burns and carbonaceous sputum is not nec- 
essarily indicative of injury. Lung edema may be 
related to generalized capillary leak syndrome and 
not to direct airway thermal trauma. Early and 
repeated airway evaluations with fiberoptic bron- 
choscopy is essential and helpful in rapidly iden- 
tifying and determining the need to intubate those 
patients who are at risk of airway compromise. 
Any patient with stridor, dyspnea, or hoarseness 
should be highly suspect. Signs of lung paren- 
chymal injury from smoke may be delayed as much 
as 24 hours. Sequential spirometry has been sug- 
gested as a way of identifying those patients at risk 
for de\eloping respiratory failure. 

Ue\ices and methods tor securmg endotracheal 
tubes in patients w ith facial burns deserve compar- 
ative trials as does the role of spirometry in iden- 
tifying those patients likely to develop ARDS trom 
burn injury and smoke inhalation. 

Ventilation during Resuscitation 

Tom Barnes identified problems with manual, 
moulh-to-mouth. and mouth-to-mask \entilation 
techniques. High peak pressures and short inhala- 
tion times divert gas into the stomach and fail to 
ventilate the lungs. Design characteristics of man- 
ual resuscitators affect their performance, and vol- 
umes and oxygen concentration ha\e been found to 
be unacceptable with some units. Tom also iden- 
tified problems with performance in extreme tem- 
peratures, particularly cold. Floppy plastic res- 
ervoirs fail in cold temperatures, and control of 
oxygen concentration can be lost. 

Tom pointed out topics for research by the res- 
piratory care community — Can the FATS tech- 
nique be easily and conveniently taught'^ Will it 
work in the acute situation'.' .Xre the newer portable 
ventilators adequate (or superior) for rescue breath- 
ing in intubated and unintubated victims? How effi- 
cacious is two-man \entilation? 

Intubation Options 

David Reines discussed intubation options with 
emphasis on the trauma \ictim. He described sur- 
gical airway techniques including cricothyroidot- 
omy for jet ventilation and needle or tracheal intu- 
bation — a simple procedure that can be mastered 
by the nonphysician and may be the only way to 
establish an airway and oxygenate the patient with 
severe upper-airway injury. Concern for cervical 
fractures in trauma patients is high, but data sup- 
porting occurrence of problems arc absent. David 
discussed the use of esophageal obturator airways 
and similar devices and expressed skepticism about 
their efficacy. Children are different from adults 
and do not fare well with transtracheal techniques 
of airway management. Evaluations of the effects 
of invasive techniques of airway management on 
tracheal anatomy and function have not been 
reported and follow-up studies are necessary. Spi- 
rometry could identify obstruction and ventilatory 
mechanics studies would be helpful. 

Thoracic Trauma 

According to Jim Hurst, 25'^r of trauma deaths 
are due to major thoracic injuries, but 859^ of chest 
injuries can be managed without surgery. Jim 
emphasized the importance (and difficulty) in rul- 


RfSPIRATOR^- CARE • JULY "92 Vol 37 No 7 


ing out aortic transection. Contrary to the usual 
teaching, the finding of a I'ractured first rib is infre- 
quently associated with aortic injury unless other 
signs are present (eg. fracture of the cervical spine 
and blood in the lung apex). The use of transport 
ventilators in the field with iiiiubated trauma 
patients is still associated with inadequate ventila- 
tion on arri\al in the emergency room. Acidosis is 
a common finding despite adequate minute ventila- 
tion. The rehabilitation of trauma victims remains a 
problem — only about 50% of those with thoracic 
injuries who survi\e e\er return to meaningful 

Evaluation of ventilation methods during trans- 
port and the use of mechanical devices during 
resuscitation prior to intubation are needed. Res- 
piratory management, respiratory rehabilitation, 
and follow-up studies with pulmonary function 
measurement after chest injury deserve active 

Hyperbaric Oxygenation 

Lynn Weaver presented an overview of the use 
of hyperbaric oxygen (HBOi) for respiratory emer- 
gencies, diving accidents, arterial gas embolism, 
and decompression sickness — the most commonly 
accepted indications for the use of HBO^. HBOt 
improves tissue oxygenation (ie. it hyper- 
oxygenates tissue), causes vasoconstriction (for 
unknown reasons), decreases gas bubble size (due 
to a direct pressure effect), and enhances immune 
system function (for unknown reasons). Lynn 
agreed with Ed Haponik that the use of HBOt in 
carbon monoxide (CO) poisoning is controversial. 
Although CO poisoning is the most common poi- 
soning in the U.S. and because CO level and signs 
and symptoms are usually unrelated, the indica- 
tions for HBO2 in this condition have not been 
established. Controlled clinical trials are being 
planned, and we hope that the answers to these 
questions will be forthcoming. A delayed degener- 
ative neurologic syndrome may occur after CO poi- 
soning. Whether use of HBO; in patients with CO 
poisoning would prevent this devastating condition 
is unknown. 

Other uses of HBO2 include treatment of anaer- 
obic (and aerobic) infections, severe crush injury, 
and support of ischemic muscle fiap grafts. The 

efficacy of HBO. in these conditions has not been 

Treatment of mechanically \entilated patients in 
monoplace hyperbaric chambers causes consid- 
erable concern. Ventilator function is affected by 
hyperbaric pressures, and alarms and monitors may 
fail. Emergencies that might occur during HBO2 
treatments need preplanned and practiced re- 

Monitoring during Resu.scitation 

Dean Hess described carbon dioxide detection 
devices for appropriate endotracheal tube place- 
ment. The color-change devices perform poorly 
during chest compression and in the presence of 
humidity and secretions. Capnography may be bet- 
ter and. in fact, end-tidal CO2 (Petco:) may be an 
indicator of the adequacy of cardiac output and tis- 
sue perfusion during chest compression. Venous 
blood gas values likewise suggest the status of the 
peripheral circulation — a lower CO. being indic- 
ative of poorer perfusion. Currently, the Petco: val- 
ues are used more for prognosis than for mon- 
itoring or modifying procedures during resus- 

Dean performed a meta analysis of outcome 
from resuscitation of hospitalized patients. 
Bystander-initiated CPR. time to resuscitation, and 
time to BLS correlated with better outcome during 
field resuscitation, but this is not true for resuscita- 
tion of hospitalized patients. Over the last 25 years, 
no change has been seen in the percentage of 
patients discharged alive after in-hospital resuscita- 
tion — despite advances in knowledge, training, and 
techniques. Subjects with the potential for fruitful 
research include the assessment of tube-placement 
detection devices, venous and end-tidal CO, mon- 
itoring for outcome prediction, and modifications 
of therapy during resuscitation. 

Chest Compression: How Does It Work? 

Tom Porter presented new information on why 
and how chest compression causes forward flow in 
the arrested heart. Despite what we have learned 
and what has been taught in the last few years on 
the contribution of the thoracic pump to blood 
flow, new information may be challenging those 




concepts. Using the transesophageal Doppler. Tom 
has studied several patients during chest compres- 
sions and has identified two patterns of cardiac 
action. The position of the mitral valve leaflets cor- 
relates with cardiac output. However, in some 
patients the mitral vai\e fails to close — in fact, the 
leaflets open even further — and these patients have 
the lowest stroke volume during CPR. Patients who 
demonstrate closure of the mitral valve ha\e the 
highest cardiac output. For the valve to close, blood 
must flow retrograde into the pulmonary veins and, 
thus, actions that raise pulmonary resistance (such 
as positive airway pressure or PEEP) may prevent 
retrograde flow and reduce cardiac output. 

RCPs have been taught that ventilation with 
compression improves cardiac output, but Toms 
work suggests that this may not be true in all cases. 
Much work remains to be done on this interesting 

Patient Transport 

The transport of critically ill patients is often a 
hazardous event. Emergencies arise but planning 
and preparation for them can reduce their impact 
on patient outcome. The final two speakers dis- 
cussed in-hospital and air transport issues. 

In-Hospital Transport 

Rich Branson described in-hospital transport 
needs: equipment, personnel, planning, and mon- 
itoring. He raised the important question. Why 
transport if the information gained from the diag- 
nostic procedure (eg, MRI or CT scan) is not going 
to contribute to patient management? From his 
study of this issue, he estimates that 15% of the 
diagnostic procedures or other reasons for transport 
result in no change in therapy. Nevertheless, in a 
controlled e\alualit)n Rich found the risk of unto- 
ward events during transport to be no higher than 
that encountered in the ICU. If it is necessary to 
transport the patient, it is important to transport the 
essential components of the ICU as well to improve 
the likelihood of appropriate care during the trans- 

Air Transport 

MarDiene Jeffs presented her experience with 
one of the oldest successful air transport systems in 
the U.S. She identified who needs to be trans- 

ported, who should be transported, and how a safe 
air transport can be accomplished. Safety of patient 
and crew are paramount. The pilot decides whether 
it is safe to fly and it is essential that the pilot be 
kept unaware of the patient's condition and that no 
pressure be put on him to make a decision to fly. 

The team concept mentioned earlier is especially 
important in air transport — with limited cabin 
space, overlapping job responsibilities, and fre- 
quent critical emergencies. Securing the airway 
takes top priority in all patient transport. Equip- 
ment is chosen to meet exacting requirements: It 
must remain functional in spite of \ ibration. noise, 
and lack of the con\entional sources of gas and 
electricity. C\)mmunication between team members 
and the home base is essential for appropriate 
ground preparation and clinical decision making. 
Ad hoc decision making rests with the transport 
team — with the decision to transport or where to go 
often changed at the scene or en route. Flexibility 
despite protocol is the rule for air transport. RCPs 
as members of the flight team must contribute more 
than just airway and ventilator skills. \x\ ideal team 
composition would be a flight nurse and an EMT- 
trained RCP. 

Continued quantification of the risks of ground. 
in-hospital, and air transport for patients and trans- 
port personnel is needed, and the participation of 
RCPs in the planning and implementation of trans- 
port policies and procedures is essential. More 
evaluation of \entilators and other equipment is 

In Conclusion 

Critical events requiring prompt recognition and 
rapid action are frequent in medical practice. 
.Almost always, a simple action can avert disaster. 
Loss of the airway, equipment failure, and inad- 
equate monitoring are the usual causes of unnec- 
essarily poor outcome. A team approach, so appro- 
priate in all of medical practice, is essential w hen a 
life-threatening condition or e\ent occurs. Because 
of their knowledge, skills, and ability to function 
effecti\ely as team members, RCPs ha\e an impor- 
tant role to play in emergency care. Many facets of 
this care nectl quality research and man\ of these 
are w ithin the realm of respiratory care. This con- 
ference has been a useful forum, and the papers 
provide a basis for continuing the dialogue on this 
exciting area of clinical practice. 




CRCE through the Journal 

The fourth annual edition of CRCE through the Journal — a way for 
members to yain continuing education credit (CRCE) by careful 
reading, thoughtful study, and test completion — appears in the fol- 
lowing pages. 

The 5()-item test is based on papers published in RESPIRATORY 
Cark from July 1991 through June 1992. The issue and page num- 
bers of the paper on which a question is based are shown in brack- 
ets following the question. You are free to consult the cited paper as 
you complete the answer sheet; however, best retention of informa- 
tion will probably occur if you read the paper in its entirety and 
then answer the questions. 

Remember CRCE through the Journal is an honor system — and the 
benefit you gain will be in direct proportion to the effort you invest. 


1. Enter your name and AARC membership 
number on the answer sheet provided with 
this issue of the Journal. 

2. Only original Answer Sheets will be graded. 
No facsimiles or photocopies will be ac- 
cepted. 35 or more correct answers provide 6 
hours of CRCE credit. 

will be available from the AARC until 1992 
CRCE Transcripts are released in early 1993. 

8. Fold Answer Sheet on the lines indicated. 

9. Place Answer Sheet in a stamped #10 enve- 
lope and mail to: 

3. Use ONLY a #2 soft-lead pencil. 

4. Mark only ONE answer for each question. 


6. If you must change your answer. ERASE 

CRCE through the Journal 

11030 Abies Lane 
Dallas TX 75229-4593 

Deadline is August 15 

1992 (POSTMARK). 
Responses postmarked after August 15 will 
NOT be processed. 

7. Correct answers will be printed in the October 
1992 issue of RESPIRATORY CARE. No scores 

Failure to follow instructions may cause tech- 
nical problems that will disqualify you. 

Please note that the acceptance of CRCE through the Journal credits for the ful- 
tlMinent of continuing education requirements in states in which respirator>' care 
practitioners are licensed depends solely on the specifications of that state's licen- 
sure law. 



CRCE through the Journal 




\y<. ^ Choose the single, most-correct answer. 

The issue and page number of the paper to which the question appUes are given in 

brackets [ ] following the question. 

Choose the most correct answer. 

a. In infants, stimulation of laryngeal recep- 
tors by liquids may result in apnea. 

b. The so-calleti central pattern generator 
essential to rhythmic breathing is probably 
located in the cerebral cortex. 

c. Breathing during REM sleep tends to be 
more rhythmic than during non-REM 

d. Apneic spells are likely to present at any 
time in infants born prematurely. 

e. When normal premature infants inhale 
increased concentrations of CO2, rate and 
depth of breathing always increase. 

[July 91:673-681] 

Choose the most correct answer. 

a. The experience with pediatric patients in 
the postoperative period may suggest that 
ECMO be e)ffered only after a period of 

b. Evidence suggests that most pediatric 
patients dying with ARE die from multi- 
system organ failure. 

c. In venovenous ECMO blood is drained 
from and returned to the right side of the 

d. Venoarterial ECMO involves cannulating 
and ligating the right common carotid 
artery — a major risk. 

e. all of the above 

|Jul\ 91:68.V692| 

3. In regard to surfactant iherap) for RDS, 
which of the following is correct? 

a. Clinical trials show that both natural and 
artificial surfactants can alter the clinical 
course of RD.S. 

b. The main reason that infants with the clin- 
ical diagnosis of RDS do not respond to 
surfactant is because not enough is admin- 

c. The artificial surfactant e\aluated in the 
U.S. contains dipalmitoylphosphatidylcho- 
line and tylo.xapol. 

d. all of the above 

e. a & c only 


4. According to the re\ie\\ by Hazinski. which 
of the following is incorrect? 

a. Agents that provoke expiratory airflow 
limitation can be classified as those that act 
directly (by stimulating airway smooth 
muscle) and those that act indirectK with 
other cells in the lung to release substances 
that reduce airway caliber. 

b. Agents that act directly include tobacco 
smoke, exercise, and intlammatory sub- 
stances released from granulocytes and 

c. If expiratory tlow limitation can be 
induced or reversed, bronchial li\per- 
reactivity is said to be present. 

d. Although much of the abnormal function in 
BPD is due to pathologic changes in air- 
ways and lung parcnch\ma. increased 
bronchomotor tone nia_\ also be a factor. 

e. Wheezing in infants unresponsi\e to beta- 
agonist therapy may be caused by tracheo- 
malacia, congenital malformations, or ob- 
structing airway lesions such as polyps or 

[July 9 1:735-743] 



CRCE through the Journal 

According to Orenstein's review of cystic 
fibrosis (CK). 

a. pulmonary indications useful in diagnosis 
of CF include atelectasis, digital clubbing, 
nasal polyps, and chronic cough. 

b. the primary components of treatment are 
pulmonary, physiologic, and gastrointesti- 

c. bronchodilators help some but not all CF 

d. the CF gene lies just behind the hypo- 

e. a and b only 

8. Which of the following is correct? 

a. "Role conflict"" can be contlict between an 
individual's time, resources, and capa- 
bilities and his defined role. 

b. "Role overload" involves uncertainty 
related to expectations of performance and 
methods of carrying out a job. 

c. "Role ambiguity"" represents a conflict of 

d. all of the above 

e. a & c only 

[August 91:829-836] 

[July 91:746-756] 

6. The hyperbaric environment and hyperbaric 

a. can affect ventilator function through the 
effect on gas density. 

b. have little effect on the function of PTC 

c. have not been known to affect rate and I:E 
of the Oxford ventilator. 

d. mandate a scavenging system for used 
pneumatic and ventilatory gases. 

e. both a & d 

[August 91:803-814] 

In Hess et aPs paper on end-tidal Pco:. 

a. end-tidal Pco: was able to correctly indi- 
cate PaC02 changes in some patients. 

b. the authors encountered difficulty in 
obtaining valid Petco: readings in some 

c. the authors suggest that end-tidal Pco2 
should never be used to indicate wean- 
ability from mechanical ventilation after 

d. the work was done to help decide whether 
to use this technique routinely to indicate 
PaCO: during weaning from mechanical 
ventilation following cardiac surgery. 

e. a and d only 

Results of the study by Hirsch et al suggest 

a. WOBi is always markedly elevated with 
the demand- valve systems of the ven- 
tilators studied. 

b. WOBi is increased by the presence of a 
bubble-through humidifier. 

c. WOBi can be essentially eliminated by the 
addition of 10 cm H.O CPAP. 

d. all of the above 

e. both b & c 

[August 91:815-828] 

[August 91:837-843] 

10. In a study of the secretion-removal effective- 
ness of the Ballard catheter, 

a. there was no difference between the num- 
bers of suction attempts required with the 
Ballard catheter and a conventional cath- 

b. the authors state that the Ballard catheter 
was effective during prolonged use. 

c. it was concluded that a hospital should use 
Ballard catheters if its budget permits. 

d. both a and c 

e. none of the above 

[August 91:844-848] 



CRCE through the Journal 

11. In ihe Drug Capsule on atlrencrgic hroncho- 
dikitors, Matheuson 

a. suggests the goals of beta-adrenergic drug 
development are increased functional selec- 
tivity and longer duration of action. 

b. defines a prodrug as one that is pharmaco- 
logically inactive but is slowly biotrans- 
formed to an active agonist. 

c. stales that an active drug that is slowly 
transformed or eliminated after absorption 
is less likely to cause side effects. 

d. emphasizes that muscle tremors and car- 
dio\ascular side effects are easily elim- 
inated from new drugs. 

e. both a & b 

[August 91:861-8631 

12. Factors to be considered when providing 
medications by aerosol nickide 

a. administration of an adequate dose. 

b. avoidance of droplet nuclei of Myco- 
bacterium riiherculo.sis disseminated by 

c. patient limitations — inspiratory tlowrates, 
breathing pattern, coordination. 

d. all of the above 

e. b & c only 

I September 9 1:9 1 6-921] 

13. Factors affecting the size of aerosol particles 
once they have been generated include 

a. heat. 

b. baffling. 

c. presence of a spacer. 

d. hygroscopicity of the solution aerosolized. 

e. all of the above 

[.September 91:93 1 -93S1 




Which of the following statements is most 

a. Any MDI can be fitted to any spacer with 
no effect on drug delivery. 

b. Dry powder inhalers are more efficient at 
high inspiratory tlowrates than at low 
inspiratory flowrates. 

c. Dr\ powder deposition is enhanced by 
head tilting and breath holding. 

d. Two inhalations from a spacer into which 
two doses of a medication have been tired 
is probably as effective as two single doses 
inhaled as one dose per breath. 

e. onl_\ b & d 

[September 91:939-95 1 1 

Studies of bronchodilator administratittn dur- 
ing mechanical ventilation 

a. all confirm small-volume nebulizer and 
MDI bronchodilator effecti\eness in me- 
chanically ventilated patients. 

b. have shown that aerosol deli\'ery is de- 
creased by the presence of an endotracheal 

c. have shown that the best indicator of effec- 
tiveness is decreased inspirator) resistance. 

d. all of the abo\e 

e. both b & c 

[September 9 1:952-976] 

In the paper by Tashkin on dosing strategies 
for airway delivery, the author suggests 

a. that results of a test based on forced exha- 
lation can be confounded by the effects of 
the test maneiner itself (airwa\ compres- 
sion and bronchoconstriction). 

b. that standard doses of bronchodilator may 
be inadequate because of impaired delivery 
due to airway narrowing. 

c. that standard doses may be inadequate 
because many drug studies were done on 
stable asthmatics and acute asthmatics may 
retjuire higher doses. 

d. that reluctance to administer higher and 
more frequent doses may stem from con- 
cern that such dosing might be responsible 
for excess asthma mortality. 

e. all of the above 

[September 9 1:977-9S71 



CRCE thn)iii>h the Journal 

17. In the paper b\ Matlli>.s and Herceg, 

a. data are presented to show that changes in 
viscoclastic properties of a solution made 
by increasing the concentration of med- 
ication in the st)lution can lead to de- 
creased pulmonary deposition. 

b. alveolar dept)sition and diffusion into the 
bronchial circulation are said to account for 
the effectiveness of pentamidine. 

c. increased airway resistance and aerophagia 
due to d\spnea are said to increase stom- 
ach deposition of aerosolized medication. 

d. all of the above 

e. a and c only 

In the conirol ol tuberculosis (TB) during aero- 
sol therapy. 

a. coughing by an infected person is an 
important factor in the transmission of TB. 

b. lllV-related TB cases are far more likely to 
transmit TB than are non-HIV-related cases. 

c. HIV-related TB cases may be less likely 
than non-HIV-related cases to transmit TB. 

d. an HIV-infected person with a positive TB 
skin test is very likely to progress to active 

e. a, c, and d only 

[September 91: 1017-1025) 

[September 91:989-993] 

18. Siy"s review of aerosol therapy in children 
indicates that 

a. the addition of ipratropium bromide aero- 
sol therapy sometimes improves the effec- 
tiveness of albuterol aerosol in acute 

b. beclomethasone aerosol therapy not only 
can help control asthma in children but 
sometimes lessens need for other anti- 
asthma medications. 

c. much research remains to be done to estab- 
lish effective and safe medication doses 
and delivery methods of aerosols in chil- 

d. Bar-Yishay et al found that I mg of crom- 
olyn sodium by MDI was less protective 
against exercise-induced asthma than 20 
mg by Spinhaler. 

e. all of the above 

[September 91:994-1007] 

19. According to Fallat and Kandal. 

a. control of e.xhaust aerosols is feasible. 

b. control of exhaust aerosols is not possible. 

c. negative-pressure rooms, or containment 
areas, can help control exhaust aerosols. 

d. tuberculosis transmission is a minor prob- 

e. a and c only 

[September 91: 1008- 1016] 

According to Waskin, 

a. aerosolized ribavirin can have adverse res- 
piratory, cardiovascular, and hematologic 
effects but never worsens obstructive lung 

b. pentamidine causes more systemic toxicity 
when given parenterally than by aerosol. 

c. pentamidine and ribavirin can be effective 
in treating pulmonary infection but not in 
preventing it. 

d. aerosolized ribavirin can be hazardous to 
caregivers, but aerosolized pentamidine 
poses no such risk. 

e. a. c. and d only 

[September 91: 1026- 1036] 

Chlorofluorocarbon (CFC) propellant gases 

a. were banned from use in 1978. 

b. were used increasingly in the 1980s but are 
being used less now. 

c. can reach the stratosphere, help deplete 
ozone, and potentially damage DNA in liv- 
ing things on earth. 

d. could be replaced by other, less harmful 

e. c and d only 

[September 91: 1037-1044] 



CRCE through the Journal 

23. According to a paper comparing two tech- 
niques t\)r determining \entiluiory reserve in 
mechanically ventilated patients, 

a. the techniques being compared were (1) 
the standard vital capacity ( VC) and (2) the 
volume inspired and the volume expired 
immediately after a maximal inspiratory 
pressure (MIP) measurement. 

b. one problem with using the VC is poor 
patient cooperation. 

c. the group able to provide a standard VC 
had a significantly greater VC than inspir- 
atory or expiratory volume after an MIP 

d. the group unable to provide a standard VC 
had a VC significantly lower than expir- 
atory volume after an MIP measurement. 

e. all of the above 

[October 91: 1085-1092] 

24. According to the study by Orens et al, which 
of the following is incorrect? 

a. MDI use saved therapist time because no 
supervision was deemed necessary. 

b. MDI use increased from 18 to 80% in 
Cleveland Clinic patients in 1989. 

c. MDI use is appropriate for all hospitalized 

d. all of the above 

e. a & b only 

[October 91: 1 099- 1104] 

25. When compression volumes were measured 
in six adult ventilator circuits, 

a. all differences in compression volumes 
between circuits were too small to be clin- 
ically important. 

b. compression factors were greater at low 
than at high ct)mpliancc settings. 

c. brand of circuit was not a factor in differ- 
ences in compression volume between cir- 

d. no differences in compression volume 
were found between nondisposable cir- 

e. compression factors were smaller at low 
than at high compliance settings. 


26. In a study comparing the tlow-by mode to the 
T-piece mode in weaning from mechanical 

a. it made little or no clinical difference 
which mode was used. 

b. the costs of the two modes were about the 

c. oxygen saturation was lower during T- 
piece ventilation than during llow-by ven- 

d. setup costs were about the same for flow- 
by at 10 L/min. How -by at 20 L/min. and 

e. total costs during prolonged ventilation 
were significantly different between the 
tlow-by and T-piece modes. 

[October 91: 1119- 11 22 1 

27. According to the paper by Chatburn. 

a. the control circuit! s) of a ventilator may be 
mechanical, pneumatic, tluidic. electric, or 

b. ventilator control schemes are intended to 
accomplish the goal of supporting some 
fraction of the patient's minute volume. 

c. during a ventilator-supported inspiration, if 
the volume waveform changes when com- 
pliance and resistance change the ventilator 
is a volume controller. 

d. all of the above 

e. a & b only 

[October 91 :li2.V 11551 

28. In the review by Nieman, 

a. standard smoke injury was defined as the 
injury resulting from a 15-minute exposure 
at tidal breathing to the smoke generated 
by burning plywood moistened with ker- 

b. standard smoke was found to damage epi- 
thelial cells and lead to increased perme- 

c. standard smoke injury was found \o be 
honn)geneous across the lung. 

d. standard smoke was found to inhibit the 
aggregation of neutrophils and their ability 
to release proteases. 

e. none of the above 

[November 91: 121 1-1217] 





CRCE through the Journal 




According to the review by Mahlmeister et al. 

a. PEP therap) eliminates the need for aero- 
solized bronchodilator. 

b. by preventing expiratory collapse PEP is 
thought to facilitate a more homogenous 
distribution o\' \entiiation. 

c. FET and PEP are essentially the same 

d. PEP is probably efficacious but it is very 

e. both b & c 

[November 91: 12 18-1228] 

During their study of PET laboratories, Wang- 
er and Irvin 

a. found statistically significant but clinically 
unimportant differences among laborator- 
ies for FVC, EEV,. and FRC by helium 

b. found testing procedures to be essentially 
uniform in the 13 laboratories included in 
the study. 

c. found little variation in the reference val- 
ues used for prediction. 

d. believe that intrasubject variability ac- 
counted for most of the results. 

e. none of the above 

[December 91: 1375-1382] 

Gooch studied the stability of albuterol and 
tobramycin when mixed for aerosol admin- 

a. because Pseiidoiuonas aeruginosa is the 
leading cause of pulmonary damage in 
patients with cystic fibrosis. 

b. because antibiotics are rarely given as aero- 

c. because it would be better to give the two 
drugs together than separately, if com- 
bining them would be effective and safe. 

d. and found that the two drugs can safely be 
combined and aerosolized for patient treat- 
ment up to 7 weeks after mixing. 

e. and found the concentrations of the two 
drugs to be unchanged at 24 hours, 48 
hours, and 7 days. 

[December 91: 1387-1390] 

32. According to the paper by Chelluri et al. 

a. bilirubin can be easily quantitated by in- 
vitro spectrophotometric analysis using the 

b. in theory, high bilirubin concentrations 
should not cause underestimation of oxy- 
gen saturation by pulse oximetry. 

c. high bilirubin concentrations do affect the 
accuracy of pulse oximetry measurements. 

d. all of the above 

e. only a & b 

[December 91: 1 383- 1386] 

33. In the ribavirin scavenging study by Kac- 
marek et al, 

a. the oxygen concentration within the inner 
enclosure varied as much as ±5% when the 
two scavenging pumps were activated. 

b. the time-weighted average for ribavirin 
was extrapolated from the NOEL for rab- 

c. one concern about ribavirin is the fact that 
it is sequestered in leukocytes and not 
cleared for 6-8 weeks. 

d. the maximum acceptable environmental 
level for ribavirin estimated by the Cali- 
fornia Department of Health is 2.7 mglrcv' 
over an 8-hour period. 

e. both b and d 


[January 92:37-45] 

Shelledy et al found that lower levels of burn- 
out were associated with 

a. improved role clarity. 

b. increased job independence. 

c. higher levels of job satisfaction. 

d. ease of obtaining time off. 

e. a, b, and c only 

[January 92:46-60] 



CRCE through the Journal 

35. A transport cart that can provide high fre- 
quency jet ventilation (HFJV) to neonates, as 
reported by Scuderi et al. 

a. should be used to provide HFJV to ail neo- 
nates during transports of 30-60 minutes. 

b. was always operable for 20 minutes on a 
single E cylinder of gas. 

c. was not studied concerning gas utilization 
resulting from changes in ventilator tlow- 
rate, inspiratory lime, and rate. 

d. has to provide all electrical and com- 
pressed-gas power used during a typical 

e. b and c only 

[Febmary 92:129-1361 

36. According to the review by Durbin. 

a. mortalit) from ARDS is primarily due to 
refractory hypoxemia and hypercarbia. 

b. some of the poor outcome from ARDS 
may be due to the toxic effects of oxygen 
on the lung parenchyma. 

c. the IVOX device is an intravascular mem- 
brane oxygenator that is much more effi- 
cient in supporting gas exchange than are 
extracorporeal membrane oxygenators. 

d. in animal studies with the IVOX, COt 
removal has been shown to be less efficient 
than oxygen delivery. 

e. both b & d 

[February 92:147-153] 

37. According to Shapiro's paper on in-vivo mon- 
itoring of blood gases, 

a. a sensor that works by detecting altered 
light is an optode. 

b. optodes consume reagents: otherwise they 
would be nn)re useful. 

c. a patient-dedicated blood gas monitor can 
warn early of physiologic changes, \\hich 
can perhaps lead to vital therapeutic meas- 

d. immediate and continuous trending of 
blood gases by monitoring would be of 
such infrequent value as to be a ""luxury." 

e. a and c only 

[Febmary 92:165-169] 



According to the re\ iew by East et al, 

a. graphically presenting information in the 
form of icons may be one strategy to help 
clinicians interpret data and make deci- 

b. a number of studies conclusively show that 
the quality of patient care is improved by 

c. computer applications in ICUs in the U.S. 
have kept pace with industrial, business, 
and personal computer applications. 

d. the LDS experience has shown that critical 
care is too complex for protocol applica- 

e. both b & d 

[Febmary 92:170-178] 

According to the re\ iew of kinetic bed ther- 
apy by Hess, which of the follow ing is cor- 

a. The decrease in FRC when a subject 
changes from the erect to the prone posi- 
tion is greater than when the subject 
changes from the erect to the supine posi- 

b. Marini et al found that in COPD patients 
saturation is higher in the sitting position 
than in supine or head-down positions. 

c. When closing volume becomes smaller 
than FRC, small airways and alveoli close 
during tidal breathing. 

d. The studies of Heaf et al suggest that 
Ptcco: in infants is greater with the good 
lung dependent. 

e. The small numbers of subjects in the pub- 
lished studies on kinetic bed therapy make 
e\aluation of some outcome \ariables dif- 
ficult or impossible. 




RESPIRATOR^' CARE • JULY "92 Vol 37 No 7 

CRCE through the Journal 




In an article on metabolic acidosis, the author 
indicates that 

a. metabolic acidosis is present in relatively 
few severely ill patients, but it is important 
all the same. 

b. metabolic acidosis is present when the 
serum pH is > 7.35 and the serum bicar- 
bonate is < 22 inmol/L. 

c. an algorithm can be valuable for finding 
out w hether metabolic acidosis is present. 

d. although mixed acid-base disorders can be 
established on the basis of blood-gas val- 
ues alone, it is best to also consider the 
patient's history. 

e. none of the above 

[March 92:258-263] 

According to the study by Dunlevy and Tyl, 
which of the following is incorrect? 

a. Mouth breathing reduces the Fio: at a 
given oxygen tlowrate. 

b. Many studies involving many subjects 
have reported the effects of mouth vs nose 
breathing on Fio; via nasal cannula. 

c. A Fenem CO^ monitor was used to verify 
the presence of tracheal ventilation. 

d. all of the above 

e. both b and c 

[April 92:357-360] 

After studying nebulizer placement in ven- 
tilator circuits at the Y-piece, the manifold 
position, and the ventilator position, Quinn 

a. recommended the ventilator position be- 
cause it delivered the most aerosol to the 

b. recommended the ventilator position be- 
cause you can use a heated-wire circuit this 

c. uses the manifold position in his depart- 
ment because they don't employ heated- 
wire circuits. 

d. did not endorse the ventilator position 
because it is unclear how aerosol is distrib- 
uted in the lung with this position. 

e. a and c only 

[May 92:423-431] 

43. According to the study by Hess and Sim- 
mons, which of the following is incorrect? 

a. Excessive expiratory resistance of a resus- 
citator valve might lead to prolonged exha- 
lation and auto- PEEP. 

b. Excessive inspiratory resistance might af- 
fect the patient's abililty to inspire spon- 
taneously through the bag. 

c. The ISO standard for bag-valve back pres- 
sure is > 5 cm H2O at 50 L/min for inspira- 
tion or expiration. 

d. Factors leading to hand fatigue during use 
of a manual resuscitator include bag com- 
pliance, endotracheal tube size, compliance 
and resistance of the patient's lungs, and 
minute ventilation. 

e. none of the above 

[May 92:432-438] 

44. According to the paper by Kacmarek, which 
of the following is incorrect? 

a. The role of the therapist in emergency care 
should encompasss airway care, CPR, 
patient assessment, drug delivery via endo- 
tracheal tube, oxygen therapy, and mechan- 
ical ventilation and transport. 

b. Defibrillation is not an appropriate task for 
respiratory therapists. 

c. The "track" record of paramedical per- 
sonnel in field intubations is comparable to 
physician intubations. 

d. Complications of orotracheal intubation in 
the field include esophageal intubation, 
vomiting, loosened teeth, soft-tissue trau- 
ma, and main-stem intubation. 

e. ACLS training should be an accepted com- 
ponent of therapists' training. 

[June 92:523-532] 



CRCE through the Journal 

45. According to the review by Wilson. v\hich is 

a. The presence of a short neck, receding jaw, 
and "buck" teeth in a subject nia\ make 
intubation ditticuit. 

b. The distance between the occiput and the 
posterior tubercle of the atlas can be 
assessed by lateral x-ray of the cervical 

c. So-called blind intubation is more easily 
and safely accomplished in the apneic 

d. So-called retrograde techniques can be par- 
ticularly valuable in patients with .severe 
maxillofacial trauma. 

e. Of the muscle relaxants used during intuba- 
tion, vecuronium probably has the fewest 
side effects. 

[June 92:533-550] 

46. According to the review by Fanta. which of 
the following is incorrect'! 

a. Simultaneous administration of broncho- 
dilators from two different classes is never 

b. Although the beneficial effect of systemic 
corticosteroids can usually be demon- 
strated within 12 hours of administration, 
the impro\ement may be \ery gradual. 

c. Subjecti\e estimates (by clinicians) of the 
severity of airflow obstruction are often 
inaccurate, both under- and overestimating 
the degree of obstruction. 

d. In acute asthma, hypercapnia is rarely 
encountered in patients with PEFR > than 
259c of normal. 

e. all of the above 

47. According to the re\'iew by Stoller, 

a. pulmonary bleeding may arise from the 
pulmonary or the bronchial circulation. 

b. causes of massi\e hemoptysis include 
tuberculosis, bronchiectasis, bronchogenic 
cancer, lung abscess, and cystic fibrosis. 

c. bronchial artery embolization has been 
reported to be reasonably successful in a 
number of case series. 

d. blood from a pulmonary source (ie. arising 
from the lung) is likely to be at least partly 
frothy and alkaline. 

e. all of the above 


48. According to the review by Thompson et al, 

a. Mapleson systems incorporate a T-piece, 
reservoir tube, self-inflating bag. and a gas 

b. during delivery room resuscitation of new- 
bt)rns. lOC/f oxygen should be a\i)ided 
because of the danger of retinopathy of 

c. the Cole-type tube is the most appropriate 
for newborn intubation. 

d. perhaps the easiest way to estimate appro- 
priate endotracheal tube si/e in the deliver)' 
room is to 'think" small (2.5 mm) for pre- 
mature infants, medium, and large (3.5) for 
full-term infants. 

e. deep suctioning is indicated for all infants 
upon del i\ cry to a\oid later problems with 

[June 92:582-599] 

[June 92:551-563] 


RESPIR.ATORY CARF • Jl'l ^' ■')2 Vol 37 No 7 

CRCE through the Journal 

49. According to the review by Haponik u liich ot 
the follow ing is incorrect'^ 

a. The importance of cyanide produced from 
nitrogen-containing polymers in early inca- 
pacitation and mortality has increased in 
recent years. 

b. Most early fire deaths are thought to result 
from carbon monoxide intoxication rather 
than surface burns. 

c. The inhalation of irritant gases may result 
in epithelial injury, increased permeability, 
and acute inflammation. 

d. Because lung bum is unlikely in victims of 
inhalation injury, the progression from 
mild pharyngeal edema to complete upper 
airway occlusion is not a major hazard. 

e. The presence of carbonaceous secretions in 
bum victims is not a good predictor of the 
presence of severe lung injury. 

50. .An article on near-drowning indicates that 

a. near-drowning has a better prognosis if it 
occurs in comfortably warm water than in 
uncomfortably cold water. 

b. hypoxemia is always to be expected in 

c. seawater near-drowning is clearly more 
likely to lead to death than fresh-water 

d. if an inert person is removed from the 
water, basic life support should always be 

e. b and d only 

[June 92:600-608) 

[June 92:609-629] 



of Events 

Nol-for-profil organiz;ilions are offered a free adveniscment of up lo eight lines lo appear, on a space-available basis, in Calendar of 
Evenls in RESPIRATORY CARE Ads for oihcr meetings are priced at $5.50 per line and require an insertion order. Deadline is the 
20th of the month two months preceding the month you wish the ad to run. Submit copy and insertion orders to: Calendar of Events. 
RESPIRATORY Carf 1 10.10 Abies Lane, Dallas IX 75229-4.5').1. 



July 15-17 in San Antonio. Texa.s. The TSRC presents its Annual 
Convention and Trade Shovs. "Kaleidoscope of Quality." Featured 
speakers include Sam Giordano. Dean Hess. Robert Demers. Rt)ben 
Kacmarek. and Neil Maclntyre. Social events include a barbecue, i-K 
fun run. dances, and an awards ceremony. Contact the TSRC E.xec- 
utivc Office (214) 680-2454. 

July 24-26 in Naples. Florida. The AARC's Summer Forum, fea- 
turins: education and management programs, is held at the Registry 
Resort. For details, refer to the special Summer Forum Program in the 
April .URCrimf.vorcall (214) 24,V2272. 

.Vugust 5-7 in .Vlbuquertjue. .New .Mexico. The .N.MSRC presents its 
1992 Annual Convention at the Pyramid Hotel. The meeting includes 
lectures and workshops, as well as presentations by AARC Executive 
Director Sam Giordano and Judy Tietsort. RN. RRT. Special features 
are the annual golf tournament. Sputum Bowl competitions. VIP 
receptions, and dance. Contact Schuyler Michael i5()>) S41-I741. 

.\ugust 6-7 in Columbus. <)hii>. Ihe Rehabilitation and Continuing 
Care Committee of the OSRC presents the "Cardiopulmonary Reha- 
bilitation and Continuing Care Forum." Topics include lung trans- 
plants for COPD patients, asthma, building patient care teams, design- 
ing exercise programs, marketing patient education programs, nicotine 
dependency, and transdermal nicotine therapy. Featured speakers 
include .Alul Mehta MD of the Cleveland Clinic Foundation; Steven 
Bia/ MD; Sandra Comett RN PhD; Sharon Balkenhol RN MSN; and 
Colleen Scrvick RRT. Contact Fori Kondas (21(1)448-1041. 

August 27 in Sacramento. California. The CSRC. Chapter II. 
presents its .Annual Seminar. "Tools of the Trade." in conjunction with 
the California State Fair. The seminar, admission to the Fair, dinner at 
the Fair's VIP tent, and California wine tasting are included in the 
admission price. Contact Marie Kearney (916) 441-7626 or Mark 
Goldstein (916) 9.'!.W469. 

September 17-18 in Tucson, Arizona. The AzSRC hosts its Annual 
Meeting at the Tucson National Resort. Golf Club, and Spa. Contact 
Becky Shocklee. .^341 N 31st St #108. Phoenix A7. 8.'iOI6. 

September 17-18 in Bethel. Maine. Ilic ,\nnual Fall Seminar, pre- 
sented by the MSRC. is held at the Bethel Inn & Country Club. Come 
get a taste of New England and its beauty in the Fall. Enjoy activities 
such as an 18-hole championship golf course, tennis, canoeing, swiiti- 
ming, an outdoor barbecue, and much more' Plenty of outstanding 
speakers, topics, and vendors present the latest in a\ailable technolo- 
gies. Contact Edward Amend. 2810 Isthmus Rd, Rumford ME 04276- 
9724. (207) .364-4581. ext 362. 

September 23 AARC Videoconfercnce. The AARC. in conjunction 
with VHA Satellite Network, presents "Aerosol Administration." one 
in a series of live satellite videiiconferences titled "Professor's Rounds 
in Respiratory Care." Featured presenters are Da\id J Pierson MD and 
Dean Hess MEd RRT. Site registration for entire staff is $245 for 
AARC members. Call (214) 8.30-0061. 

-September 24-25 in Indianapolis. Indiana. The ISRC presents its 
Fall Conference at the Marriott Inn. The auards ceremony and Sputum 

Bowl are held on Thursday. Contact Jan Doherty (800) 327-3152 or 


September 29-30 in Honolulu. Hawaii. The HSRC holds its I9th 
Annual Respiratory Care Conference at the Hilton Hawaiian Village 
Hotel. Contact Helen M Ono RRT. 1717 Palolo Ave. Honolulu HI 


September 30-()clober 2 in Traverse City. .Michigan. Ihe MSRC 
presents its Annual Fall Conference at the Shanty Creek/Schuss Moun- 
tain Resort. The general session focuses on asthma management, crit- 
ical care, ventilation and waveform interpretation, nutrition, and risk 

' management. Also, the Cardiopulmoniiry Diagnostics Membership 
Section presents pulmonary function and sleep disorder testing. Social 
events include a wine-and-cheese reception, golf outing, cookout. and 
dance. Come join us for another successful conference, and enjoy the 
beautiful colors of Fall in Michigan. Contact Beth Hill RRT. Bay Med- 
ical Center, Respiratory Care Dept. 1900 Columbus .Ave. Bay City MI 

October 14 in .Auckland. New Zealand. The NZSRC presents its 

Annual Scientific Meeting at the .Aoiea Centre. The meeting precedes 
the Australian-New Zealand Intensive Care Society Conference. Con- 
tact Graeme A'Court. PO Box 101 4S. Balmoral. Auckland. New Zea- 
land. (643) 640640. 


July 29-31 in Salt Lake City, Utah. The Rocky Mountain Center for 
Occupatit)nal and Environmental Health presents "Training for Pul- 
monary Function Testing." a 2 1/2 day course for personnel involved 
in the performance and interpretation of screening spirometry. Call 
(801) 581-5710. or write Program Coordinator. Rocky Mountain Cen- 
ter for Occupational and Environmental Health. Building 512. Uni- 
versity of Utah. Salt Lake City UT 84 1 1 2. 

.August 17-19 in Washington. DC. The Centers for Disease Control. 
Food and Drug .Adniinisiratum. and Occupational Safety and Health 
.Administration sponsor "Frontline Health-Care Workers; .A National 
Conference of Device-Mediated Bloodbome Infections" at the Hyatt 
Regency Washington on Capitol Hill. Contact Laura Timperio. PACE 
Enterprises Inc. 17 Executive Park Dr NE. Suite 200. Atlanta GA 
.30329. (404) 633-8610. fax (404) 633-8745. 

Septembir 9- 1 1 in Captiva Island. Florida. The Suncoast Pul- 
monary Seminar is held at the South Seas Plantation Presentations 
cover pediatric, neonatal, critical care, and management topics. .Speak- 
ers include Neil Maclntyre MD and George Burton MD. Rich Branson 
RRT. and Judy Tietsort RN RRT. Contact Robert Sobkowiak (813) 

October 'MO in \ ail, Colorado. The Colorado Advanced Life Sup- 
port Committee holds its Biennial Resuscitation Conference. "Fresh 
Perspectives on .ACl.S and P.ALS." at the Westin Hotel. Join Joseph 
Oniato MD and James Seidel MD. among others, for state-of-the-art 
therapy and a review of the Dallas ECC Conference during the beauti- 
ful Fall sea.son in the Rockies. Contact Colorado ALS. PO Box 
440895, Aurora CO 80044. (.303) 363-8380. 


RISI'lR ATORV CARE • JULY "92 Vol .^7 No 7 

Notices of competitions, scholarships, fellowships, examinalion dales, new educational programs, and ihe like will be listed here free of 
charge. Items for the Notices section must reach the Journal 60 days before the desired month of publication (January I for the March 
issue. February 1 for the April issue, etc). Include all pertinent intbniiation and mail notices to RESPIRATORY CARt Notices Dcpl. 
1 1030 Abies Lane. Dallas TX 75229-4593. 



Centers tor Disease Conlrol. Prevention and control of intluen/a: reconiniendations of the Inimuni/ation Practices Advisory Committee (ACIP). 
MMWR 1992i4UNo. RR-9):I-I7. [Some excerpts are provided below.) 

Persons who are clinically or subclinically infected and who attend or live with high-risk persons can transmit influenza virus to them. Some high-risk 
persons (eg. the elderly, transplant recipients, or persons with .AID.S) can have low antibody responses to influenza vaccine. Efforts to protect these 
high-risk persons against inlluenza may he impro\ed by reducing the chances of exposure lo mllucn/a from their care providers. Therefore, the fol- 
lowing groups should be vaccinated: 

1. physicians, nurses, and other personnel in both hospital and outpatient-care settings who have contact with high-risk persons among all age groups, 
including infants. 

2. employees of nursing homes and chronic-care facilities who have contact with patients or residents. 
i. providers of home care to high-risk persons (eg, visiting nurses, volunteer workers). 

4. household members (including children) of high-risk persons. 

Inactivated inlluenza vaccine should not be administered to persons known to have anaphylactic hypersensitivity to eggs or to other components of the 
influenza vaccine without first consulting a physician (see Side Effects and Adverse Reactions). 

Beginning each September, when vaccine for the upcoming influenza season becomes available, high-risk persons who are seen by health-care pro- 
viders for routine care or as a result of hospitalization should be offered influenza vaccine. Opportunities to vaccinate persons at high risk for complica- 
tions of influenza should not be missed. 


The optimal time for organized vaccination compaigns for high-risk persons usually is the period between mid-October and mid-November, 

Copies can be purchased from Superintendent of Documents. U.S. Government Printing Office. Washington DC 20402-932.5 or via telephone (202) 



CRTT Examination 

Fee Schedule 


Entry Level CRTT — new applicant: 

$ 90.00 

Applications Accepted Beginning: March 1. f992 

Entry Level CRTT — reapplicant: 

$ 60.00 

Application Deadline: May 1. f992 

RRT Wntten and Clinical Simulation— 


new applicant: 


.Applications Accepted Beginning: July I. 1992 

Written Registry Only — new applicant: 

$ 90.00 

Application Deadline: September 1. 1992 

Written Registry Only — reapplicant: 

$ 60.00 

Clinical Simulation Only new and reapplicant 


RRT Examination 

Entry Level CPFT new applicant: 


Entry Level CPFT— reapplicant: 

$ 80.00 


Advanced RPFT — new applicant: 


Applicalums Accepted Beginning: June 1. 1992 

Advanced RPFT — reapplicant: 


Application Deadline: August 1. 1992 





$ 60.00 

RPFT Examination 

RRT Recredentialing: 


Written Registry Examination 


$ 60.00 

Applications Accepted Beginning: July 1. 1992 

Clinical Simulation Examination 



Application Deadline: September 1. 1992 

CPFT Recredentialing: 


$ 80.00 

RPFT Recredentialing: 






8310 Neiman Road • Lenexa, 

Kansas 66214 • (913) 599-4200 




Manuscript-Preparation Instructions for 
Authors and Typists 

General Information 

Respiratory Care welcomes original manuscripts related to 
respiratory care and prepared according to these Instructions. 
Perfection is not required, but efforts in that direction are 
appreciated. Computer diskette submissions are encouraged 
and may reduce processing and review imie. See requirements 
in these Instructions. 

Editorial consultation is available by telephone or letter at 
any stage of planning or writing. Specific guidance (in printed 
form) will be provided on request for writing a research paper, 
a case report, an evaluation, a review, overview, or update or a 
book review; for converting to and from SI units; and for in- 
house manuscript review. For typists, a model manuscript, list 
of journal name abbreviations, and copy of these Instructions 
is available. Write to Respir.vfor'i' Cark. 1 1030 Abies Lane, 
Dallas TX 75229-4593. or call (214) 243-2272. 

Manuscripts are reviewed by authoritative referees in a dou- 
ble-blind manner. Accepted manuscripts may be copyedited 
for clarity and style; authors receive galleys to proofread 
before publication. Published papers are copyrighted by the 
publisher and may not be published elsewhere without per- 

Publication Catej^ories Article: A report of an original investigation (a 

Evaluation of Device/MethodA"echnique: A description and 
evaluation of an old or new device, method, technique, or 

Case Report: A report of a clinical case that is uncommon, or 
was treated in a new way. or is exceptionally instructive. All 
authors must have been associated with the case. A case- 
managing physician must either be an author or furnish a letter 
approving the manuscript. 

Review Article: A comprehensive, critical review of the lit- 
erature and state-of-the-art sununary of a pertinent topic that 
has been the subject of at least 40 published research articles. 

Overview: A critical review of a pertinent topic about which 
not enough has been published to merit a Review Article. 

Update: A report of subsequent developments in a topic that 
has been critically reviewed in this journal or elsewhere. 

Point of View Paper: A paper expressing personal but sub- 
stantiatcil opinions on a pertinent and controversial topic. 

Special Article: A pertinent paper not fitting one of the fore- 
going categories may be acceptable as a Special Article. It is 

advisable to consult the Editor before writing or submitting 

such a paper. 

Editorial: A paper drawing attention to a pertinent concern; it 
may present an opposing opinion, clarify a position, or bring a 
problem into focus. 

Letter: A signed communication about prior publications in 
this journal, or about other pertinent topics. Tables and illustra- 
tions may be included. Type double-spaced, supply a title. 
mark "For publication." 

Blood Gas Corner: A brief, instructive case report involving 
respiratory care blood data — with questions, answers, dis- 

PFT Corner: Like Blood Gas Comer, hut involving pul- 
monary function tests. 

Test Your Radiologic Skill: Like Blood Gas Corner, but 
involving pulmonary medicine radiography and including one 
or more radiographs, may involve imaging techniques other 
than conventional chest radiography. 

Review of Book, Film, Tape, or Software: A balanced, cnt- 
ical review of a recent release. 


Prior and Duplicate Publication: Work that has been pub- 
lished or accepted elsewhere usually should not be submitted. 
In special instances, the Editor may consider such material, 
provided that permission to publish is given by the author and 
other publisher. Please consult the Editor before submitting 
such work. 

Authorship: .All persons listed as authors should have par- 
ticipated in the reported work and the shaping of the manu- 
script; all should have proofread the submitted manuscript; and 
all should be able to publicly discuss and defend the paper's 
content. A paper with collective (corporate) authorship must 
specify the key persons responsible for the article. Authorship 
is not justified solely on the basis of solicitation of funding, 
collection or analysis of data, provision of advice, or similar 
services. Persons performing such ancillary services may be 
recogni/ed in the .Acknovv ledgments section. 

Conflict of Interest: Authors of research or evaluation papers, 
points of view, or editorial are asked to disclose on the manu- 
script's title page any liaison or financial arrangement they 
may have with a manufacturer or distributor whose product 
figures in the submitted manuscript or with the manufacturer 
or distributor of a competing product. (Such arrangements will 
not disqualify a paper from consideration and will nol he dis- 
closed to reviewers.) 




Preparation ol'thi' Manuscript 

Details about Sections: 

Note: in addition ui rcadiny these Instruclions. authors and 
typists can benefit Irom inspecting papers recently published in 
Respiratory Carh and using them as models. 

General Specifications 

Type on one side ot while bond paper. 216 x 27^ mm (8 in. x 
II in.) with margins of at 25 mm (I in.) on ail sides of the 
page. Douhle-space the entire manuscript (three lines per ver- 
tical inch). Number all pages in upper-right corners. Indent 
paragraphs 5 spaces. Do not justify. Do not underline titles, 
headings, or other words. Do not type authors' names or other 
identification anywhere except on the title page. Repeat title 
only (no authors) on the abstract page. Begin each of the fol- 
lowing on a new page: title page, abstract, text, product- 
sources list, acknowledgments, reference list, each table, each 
appendix, list of figure legends. Use standard English. Employ 
the first person and active voice (eg, "We believe that pigs can 
fly") rather than the "obscure person" and passive voice (eg, "It 
is believed that pigs can tly") — because the latter obscures the 
identity of the responsible party (the believer). 

Headings in Text: Center main section headings on the page 
and type them in capital and small letters (eg. Introduction, 
Methods, Results, Discussion). Begin subheadings at the left 
margin and type them in capital and small letters (eg. Patients, 
Equipment, Statistical .Analysis). Do not underline or darken 
section headings or subheadings. 

Manuscript Structure 

Most kinds of papers have standard parts in a standard order, 
as shown hereafter. However, papers can vary individually, 
and not all papers will have all the parts listed here. 

Research Article: Title Page, Abstract, Introduction, Meth- 
ods, Results, Discussion, Conclusions, Product Sources. 
Acknowledgments. References. Tables, Appendices, Figure 

Evaluation of Device/Method/Technique: Title Page, Ab- 
stract, Introduction, Description of Device/Method/Technique, 
Evaluation Methods, Evaluation Results, Discussion, Conclu- 
sions, Product Sources, Acknowledgments, References, 
Tables, Appendices, Figure Legends. 

Case Report: Title Page, Introduction, Case Summary, Dis- 
cussion, References, Tables, Figure Legends. 

Review Article: Title Page, Table of Contents. Introduction. 
Review of the Literature, State-of-the-Art Summary, Acknowl- 
edgments. References. Tables, appendices, and illustrations 
may be included. Other formats may be suitable. 

Point of View Paper: Title Page, Text, References. Tables 
and illustrations mav be included. 

Title: Make the paper's title as specific, clear, and yet as short 
as you can. 

Title Page: List (a) title of the paper; (b) full names of all 
authors, with academic and credential letters, professional 
titles, and institutional affiliations; (c) name, address (include 
building and/or room number for courier .service), telephone 
number, and Fax number of corresponding author: (d) name 
and address for reprint requests: (e) sources of support such as 
grants, equipment, drugs, and supplies; (f) name of organiza- 
tion, location, and date of any meeting at which a version of 
the paper has been presented; (g) disclosure of financial rela- 
tions of any author with commercial products or interests con- 
nected with the paper — or with competing products or inter- 
ests; (h) name, title, and affiliation of statistical consultant, if 
any; and (i) disclaimers, if any. 

Abstract: (required only for research articles and evaluations 
of devices/ methods/techniques). The abstract must summarize 
what was studied; why and how it was studied; the results, 
including important data and statistical significance: and con- 
clusions drawn from the results. All information in the abstract 
must also appear in the paper itself Do not cite references in 
the abstract. The abstract for a research article should include 
the following headings (in all capital letters), appropriately 
placed within the abstract and followed by colons: BACK- 
abstract for a paper evaluating a device/method/technique 
should include the following headings: BACKGROUND. 
abstract should be all one paragraph, not indented, and not 
longer than 250 words. Center title, typed in capital and lower 
case letters, over abstract. 

Introduction: Briefly describe the background of the work or 
the paper. Cite only pertinent references, and do not review the 
subject extensively. Do not include data or conclusions from 
the work reported in your paper. In a research paper, end this 
section with a clear statement of the research question(s) or 

Methods Section (in a research paper): Describe the selection 
of patients, controls, or laboratory animals. Give details about 
randomization. Describe methods for blinding of observations. 
Give numbers of observations. Report losses to observation 
(eg, dropouts or disqualified subjects), listing numbers of sub- 
jects or data sets lost, when lost, and why lost. Describe meth- 
ods in sufficient detail to allow other workers lo replicate your 
work. Give references to established methods; provide refer- 
ences and brief descriptions for methods that have been pub- 
lished but are not well known: describe new or substantially 
modified methods, give reasons for using them, and evaluate 
their limitations. Report calibration of measuring devices. 

Drugs — Identify precisely all drugs and chemicals used, giving 
generic names, doses, and routes of administration. If desired. 



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ii'- '1. uppr'rpriat^. rnay t* iri' liirle/l I'rovi'le a ( lent 
'f(rt(«f i»w#y' ttm^fn^ Uif fmtU^ft clfher «« (h# ftirl of the f >l* 
6m<ii^in «e6f)/»fi rrf in a t^ptitMi^ CimcimUm^ w iion 

PflMiH-l *UtHf(-^ pMltH WhMi fn'ff^ (tirtri tdrw' / 0(fi((p»>r(iiil 
fn'riUi'l:, ml \iii\inii ^tntisti/ nl i;/if('//rtf(». rttp m^ndOfir'd in llw 
pmpM, liM maniifa' tufMs' nam^s, Mdes, rtrrrl slufen or ('Oimlries 
hfi « ^rrrfliKl ,<?M(r«*» f«^ nflw (h* («*(, Pat tmoh fclfirt ttf 

pffx-lucf, list the generic term, hrawl name awl morlcl number, 
manufacturer's name, city, and state f>r wnintry Man 
ufactiirer's siiggeste/l prif^e sthrml'l be incliirle^l when Ihr. study 
orevalciati'in has c/ist implications for example; 

Vfanual fcesiis(;(fatr>fs: 

Bagftasy. Kes0ronics fnc. Murrysville PA. $2f),5f) 

(^le Blue, Vital .Signs (ru.. Totowa N.(, %l')M 


72f)f). Puritan Bennett Corp. f>vcrland Park K.S 

Bearfiub. Bear Mwlical Systems, Riverside CA 

Afl<n/»vi'le/lgments Pa(((!; (yn this page ymj may recrignixe thr 

servK^s of pcrwins whr> marie ancillary Mintribuiions to thr 
work rif the maniis<:ript .Such services might be advice about 
rtrieth'i<U>logy. data w>llc<;tirirt. statistical advi<;e or analysis; 
e<|uipmcnt sclctlifm r>r ripcratirm. wifjpcralirin as caregiver, 
patient, rir suhjett; maniist^ripf preparation; in'hoiise review; 
and other servir^.s Par^h acknowlwlgmeni must spe<.ify the ser 
vi(^ renrlerwl Name/1 ()ers<>ns must provide wriiien agrcemrni 
faccr>mpanying submitterl manuscript) Ui he sti rc<;t)gn(/e<l. 

kf^f rt'Tm-n 

Vfm rif (Jefer»rr»<-«; References are (is«<l lt> support siatctnenis 
of fact. Ill indicdie s<>ur<:es r>f infofinaiion. or to guide re(i<lers 
fr> furlhrr inforrnatirrfi He careful (o inakr clear in Ihr lexl Ihr 
reas'in fr>r a spe<;ific (ilatlrin (ie, dr> not imply t:iippori of a 
sfAtement rrf facf by citing a referent^e that simply addrrssrs 
ttie issue). CUe rmly srntfces that have atlually heen consulini 
and pvaliiate/l by thr jiuthors f ilr only iiuhlhhml or miffilrfl 
material file original ariK Irs in prrlirrni c in;, 
r«tview articles, ahstracts, p<l)l/»rials, or tellers. Avoid tMtim 
ahslrar^is mr»re ItiMti < years old anri make every rffori to drin 
mine whether an abstract has been subsp<(ufnlly publlshrd as a 
frdi Irrigth prtfirr Avoid citing non P.iiylKli lungiiiigr soiin rs 
When (iling froni a book, specify the page niiuibrrs unless you 
«rf« eirlfljK rtwt sflflr* hr»r»k, If ymi cjl» n paper ihai has hern 
(»c<*pfed hut ritit yr-l puhlished T'lti prrss"). provide a ( opy oi 
the p»(jpr lr> the (vlilor whrti you submit yoiit iniuiiisi dpi 

|jo noi (He unpublished observalloiis as refetriurs distend. 
Irlentify written (not ritnb (oininiinidillons in parriiltiesrs in 
the le*l, giving the wfller's name (iiid lo( iillon and the dale i<l 
lh« (^rmtniirilf atltiii Infirruiiillon from umnusi ripis submiiieil 
htd not yet (Kcepled should be i ilefl In llir lenl (in pmrnllieses) 
as "unpublished obsefvntlons " 

f Ming Hftfrftu^i* In <h«> li>iili Ihr firsi tpffifpiK e you clip Is 
XefpretKe I, Ihe tiPKl Is Kpferpticp /, pic Aflpr Dip fitsi cIlMllon 
of a tFtfitnmr, usp lis original nuinliFt If you i Me It (igiilii liilei 
in die pn|ier (IIP rpfpteiii es by siipeisi ilpl, full ol/e. iioilili 
niiinrials I'o not eni loije in paienllieses If n i lliillnn niiiiii ml 
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nflpr (tnilsldP) llip (diium, spitilcolott, ot pptlod im>i i.iIum 
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Number tables as Table 1. Table 2. etc. consecutively in the 
order of their tlrsl mention in the text. Place the number and a 
descriptive title above the table (not on a separate page). Give 
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To key footnotes to the table body, use conventional designa- 
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placing them superscript in the table body. 

Double-space all elements of tables, including titles, column 
headings, data, and footnotes. Continue a deep table on fol- 
lowing pages. Do not use horizontal or vertical rules. Do not 
submit tables as photographs, or reduced in size, or on oversize 
paper. Use the same typeface as in the text. Supply the name 
and version of any table-building computer program used. 

Appendices: .Mathematical calculations, documents, and other 
matter that would clutter the mam article can be displayed in 
appendices. Number them as Appendix 1 , Appendix 2, etc, and 
refer to them in the text. Give each appendix a descriptive title 
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etc, according to the order in which they are first mentioned in 
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and large enough to remain legible when downsized for pub- 
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figure on the back with a stick-on label showing figure num- 
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title. Omit author's name. Cover label with clear tape so ink 
will not smudge other prints. Do not use staples or paper clips, 
and do not write heavily on the backs of prints. 
Radiographs: If possible, submit radiographs as full-size cop- 
ies of films, not as prints. Prints may be acceptable, but full- 
size films are preferable in order to display better detail in pub- 
lished figures. Be sure all figures are cited in the text. If any 
figure has been published before, include copyright-holder's 
written permission to use it. 

Figure Legends: Its legend should, to the extent possible, 
make a fiaure understandable without referring the reader to 

the text. Type figure legends double-spaced, on a separate 
page, as Fig. 1, Fig. 2. etc. When symbols, arrows, numbers, or 
letters are used to identify parts of a figure, identify and 
explain each part clearly in the legend. In photomicrographs, 
explain the internal scale and methixi of staining. If a figure 
has been published before, acknowledge the original source in 
its legend (permission must be obtained prior to use, of 

Units of Measurement: Give measurements of length, height, 

weight, and \iilume in metric units appropriately abbreviated. 
Gi\e temperatures in degrees Celsius. Give blood pressures in 
millimeters of mercury (mm Hg). Report hematologic and clin- 
ical-chemistry measurements in conventional metric system 
and in SI units (International System of Units). Show gas 
pressures (including blood gas tensions) in torr. List SI equiv- 
alent \ alues. when possible, in brackets following non-SI val- 
ues—for example. 'PEEP. 10 cm H:0 [0.981 kPa]." For con- 
version to SI, see Respir.mory Care 1988;33:861-873 (Oct 
1988) and I989;.34:145 (Feb 1989). 

Arithmetic: Carefully double-check all arithmetic before sub- 
mitting the paper. Accuracy is the author's responsibility; 
errors are common! 

Abbreviations and Symbols: Use standard abbreviations and 
symbols. Avoid creating new abbreviations. Avoid all abbre- 
viations in the title and unusual abbreviations in the abstract. 
Use an abbreviation only if the term occurs several times in the 
paper. Write out the full term the first time it appears, followed 
by the abbreviation in parentheses. Thereafter, employ the 
abbreviation alone. Never use an abbreviation without defining 
it. Standard units of measurement can be abbreviated without 
explanation (eg. 10 L/min. 15 torr, 2.3 kPa). If you employ a 
great many abbreviations and symbols, provide a double- 
spaced list of them, with their definitions, in alphabetical 

Please use the tbllowing forms; cm H:0 (not cmH:0), f (not 
bpm), L (not 1), L/min (not LPM, l/min. or 1pm), mL (not ml), 
mm Hg (not mmHg). pH (not Ph or PH). p > 0.001 (not 

p>0.()()l ). s (not sec). SpO; (pulse oximetry saturation). 

Computer Diskettes: .-X manuscript may be submitted on a 
Macintosh or IBM-compatible diskette. Macintosh docu- 
ments on 3.5 in. diskettes written in Microsoft \\ord ver- 
sions 4.0 and 5.0 are preferred. .Acceptable programs are 
MacWrite, Macintosh Works. Word for Window version 3.0; 
Window sWrite; WordPerfect versions 4.1, 4.2. 5.0; WordStar 
releases 3.3, 3.45. 4.0. 

Label each diskette with date: author's name; name of word- 
processing program and version used to prepare documents; 
and filename(s). If not enough space is available, list contents 
on disk jacket or an attached note. Do not write on a diskette 
except w ith a felt-tipped pen. 

Tables and figures must be in their own separate files, with 
.software identified. 




Together with diskette, supply three hard copies of the manu- 
script. Do not papercHp a dislvette to its hard copy. 

Proofreading and In-house Review: Have all authors proof- 
read the manuscript for content accuracy and language. Con- 
sider having the manuscript reviewed in-house by colleagues 
before submitting it. 

Submitting the Manuscript 

Use the checidist below to make sure the manuscript is ready 
for mailing. Mail three copies of the manuscript and figures to 
RESPIRATORY CARE, 11030 Ables Lane, Dallas TX 75229- 
4593. Do not Fa.\ manuscripts. Protect figures v\ ith cardboard 
to prevent bending. A computer diskette submission must be 
accompanied by the requisite three hard copies. Keep a copy 
of the manuscript and figures in your files in case of loss. You 
will be sent an acknowledgment that your manuscript has been 

Cover Letter: The manuscript must be accompanied by a cov- 
ering letter signed by all the authors. The letter must specify 
the intended publication category and. when there are two or 
more authors, state that "We. the undersigned, have all par- 
ticipated in the work reported, proofread the accompanying 
manuscript, and approved its submission for publication." 

Permissions: The manuscript must be accompanied by copies 
of permissions to reproduce published material (figures or 
tables); to use illustrations of, or report sensitive personal 
information about, identifiable persons; or to name persons in 
the Acknow ledgments section. 

Author's Checklist: 

1. Does paper fit a listed publication category? 

2. Does the cover letter meet specifications? 

3. Is the title page complete? 

4. Is double-spacing used throughout entire manuscript? 

5. Are all pages numbered in upper-right corners? 

6. Are paragraphs indented 5 spaces? 

7. Are all references, figures, and tables cited in the text? 

8. Are references typed in requested style? 

9. Have SI values been provided? 

10. Has all arithmetic been checked? 

1 1 . Have generic names of drugs been provided? 

12. Have necessary written permissions been provided? 

13. Have authors" names been omitted from text and figure 

14. Have copies of "in press" references been provided? 

15. Has manuscript been proofread by all authors? 





in This Issue 

Barnes. Thomas A 673 Jeffs, MarDiene 796 

Branson. Richard D 775 Nixon. JV 769 

Durbin, Charles G Jr 807 Ornato. Joseph P 769 

Eitel, David 739 Porter. Thomas 769 

Hess. Dean 739 Reines. H David 695 

Hurst. James M 708 Weaver, Lindeli K 720 

in This Issue 

Bear Medical Systems 652. 666 Inslriinieniation Labs Cover 2, 641, 658 

Burroughs Wellcome Co 656a Meircx Research 664 

Ciba-Coming Diagnostics 642 Nellcor Inc 644, 669 

Dey Laboratories Cover 3 Respironics 650 

HealthScan Products 655. 663 Ross Laboratories 647, 648 

HR Inc 654 Sherwood Medical Cover 4 

Impact Medical 661 

832 R[-,SPiR.\TOR^- CARF • JULY "92 Vol 37 No 7 

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Quality Control Products & 

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Albuterol Sulfate 


HealthScan Products 

Assess Peak Flow Meter 


HealthScan Products 




Aerotherm Dryer 


Impact Medical Inc 

750 Transport Ventilator 


Instrumentation Labs 

BG3 Blood Gas Analyzer 


Instrumentation Labs 

IMPACT Blood Gas Data 



Metrex Research Corp 

ColdSpor Disinfectant 


Nellcor Inc 

Corporate Ad 


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Sherwood Medical 

New Voldyne Incentive 

Deep Breathing Exerciser 


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DEY. ' 

I- Type of Instn/Practice 

1 J Hosp 500 ot more beds 

2, J Hosp 300 10 499 beds 

3 -1 Hosp 200 10 299 beds 
4. J Hosp 100 10 199 beds 
5-1 Hosp <t00 or less beds 

6 -I Skilled Nursing FaoIiTy 

7 J Home Care Practice 

8 _) School 

II. Department 
A J Respiratory Therapy 
B J Cardiopulmonary 
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III. Specialty 
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|g Corporation, 
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DALLAS, TX 75229-9691 










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A Figh Quality 



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For additional product 
information call: 


To order: 


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2751 Napa Valley Corporate Drive ■ Napa, CA 94558 
800/869-9005 707/224-3200 FAX 707/224-3235 

J^SKr, solution ^^ 




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•Potency expreed as albuterol 

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Volumetric Incentive Deep-Breathing Exerciser 

The accuracy of Voldyne, in a new size, matched to geriatric 
patients and patients with smaller lung capacities. 


Voldyne 2500 ... 

■ A smaller, ligliter flow cup reduces the work of breathing, thus 
improving patient performance and progress. 

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reliability and superior accurao,- of inhaled lung volume 

■ Volume incentive spirometry improves assessment of patient 

progress by eliminating the guesswork associated with spirometers 
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■ Graduations printed on both sides of the unit allow the therapist to 
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